Heinemann Science Scheme Book 1 - Pearson Schools

Teachers' resource Pack

Heinemann Science Scheme Book 1 Unit K Sample pages Please note: There is additional material to be added to this unit, for example, `Test yourself' answers pages; charts showing Science 1 opportunities etc. There may still be some uncorrected errors in these pages.

1 q I Bradley, C Tear, M Winterbottom, S Young, 2001, The Heinemann Science Scheme

2 K1 Where do we come across forces?

Learning objectives

(from QCA Scheme of Work) Pupils should learn: l l l

l

l

K2 Why do things float?

K3 Using density

l

l

l

l

K4 How do forces balance?

l

l

Teaching activities

about a range of forces how to measure forces that mass is the amount of matter, measured in kg that weight is a force, measured in newtons that weight is caused by gravity acting on a mass

l l l l

that when objects are immersed in water there is an upthrust on them

K2 Core: Why do things float?

that when objects float, upthrust is equal to weight to draw conclusions from experimental results that upthrust is different in different liquids

K3a Core: Finding volume K3a Help: Measuring the volume of an object K3b Core: Finding the weight of water K3b Extension: Boats and ships

that when an object is stationary the forces on it are balanced that the direction of a force can be represented by an arrow

Learning outcomes

(from QCA Scheme of Work) Pupils:

l

l

l

l

l

l

Homework resources

Specials

Extension resources K1 Mass and weight

(learning support)

K1 Forces

K1 Forces (Completing a table, cloze passage)

state that all objects weigh less in water than in air recognise that objects which float show a zero weight reading

K2 Floating and sinking K2 Displacement

K2 Floating and sinking (Cloze passage)

state that an object will float if it is less dense than water state that some liquids produce a greater upthrust on an object than others

K3 Density

K3 Volume of water/Weight of water/Boats and ships )Cloze passages, labelling)

identify the forces on an object and the direction in which they are acting demonstrate understanding that forces on a stationary object are equal

K4 Balanced forces

K4 Balanced forces (Completing a diagram, questions)

Scheme of Work

identify forces use a forcemeter explain observations distinguish and use the relationship between mass and weight

Unit K Forces and their effects

q I Bradley, C Tear, M Winterbottom, S Young, 2001, The Heinemann Science Scheme

Book spread

K5 Forces and their effects

Learning objectives

(from QCA Scheme of Work) Pupils should learn: l

l

l

l

l

l

l

l

l

that friction is a force that opposes motion how friction between two surfaces can be reduced with a lubricant that frictional forces can be useful that stopping distances of vehicles relate to frictional forces and speed about speed and the units in which it is measured how to interpret distance/time graphs qualitatively about factors affecting frictional forces to investigate one variable while keeping others constant to represent quantitative data in a graph

Learning outcomes

(from QCA Scheme of Work) Pupils: l

l

l

l

l

K6a Core: Stretching a spring K6b Extension: Stretching a rubber band K6a/b Help: Analysing results

l

l l

Homework resources

(learning support)

Specials

Extension resources K5 Resultant Forces

explain differences in behaviour in terms of frictional forces identify characteristics of lubricants identify that stopping distance . . . relates to speed explain in words the unit of speed describe the journey shown in a speed/time graph

K5 Friction

K5 Forces (Wordsearch)

identify and explain which variables need to be kept constant in order to obtain reliable data plot a suitable graph make and test a quantitative prediction

K6 Springs and stretchy things

K6 Stretching springs (Interpreting a graph)

3

Scheme of Work


K6 Investigating forces

Teaching activities

Unit K Forces and their effects

Book spread

Teacher and technician notes

Why do things float? Resources available

K2

Materials required

Core sheet

Using forcemeters to measure upthrust

CD-ROM

All text customisable

Links with Book 1

SoW

Sc1

K2

7K page 1

2e±h, k, m, p

Per group l

One forcemeter. Suitable scale for heaviest and lightest object, and to measure difference in water.

l

One container for water. It must be wide enough to take the objects when hanging on the forcemeter, so that it is possible for object to be immersed in water without touching the bottom. If the water flow from taps is slow, large buckets or bowls should only be used if they can be filled beforehand. With small objects, 500 ml plastic beakers would be adequate.

l

One set of objects for weighing. Objects should have easy method for attaching to forcemeter and should include:

Safety Glass containers are unnecessary and should be avoided ± plastic washing-up bowls are better.

Activity procedure 1 Students will use a forcemeter to measure

Wooden object, such as a block

and record the weight of the first object.

Heavy wooden object ± could be the same block as above, must weigh less than the light metal object

2 They will then lower the object into water. 3 If the object sinks then they record the weight once the object is completely immersed in water ± taking care that it has not settled on the bottom of the container.

Solid plastic object ± such as a toy, cutlery Hollow plastic object ± such as a ball, bottle, or duck, must be watertight

4 If the object floats they should lower the

Light metal object ± such as a 50 g weight

forcemeter enough to be sure that it really is floating on its own ± in fact until the forcemeter reads zero, and record that the weight is now zero.

Heavier metal object ± such as a 500 g weight A stone or piece of rock

5 Repeat with all the objects supplied.

Running the activity Weighing the object dry first, then lowering into water should reduce spills and will be quicker than weighing all the objects dry and then putting them all on the forcemeter again. If the number of objects is limited so that groups are sharing them then there is a case for doing all the dry weighing first. Take care that in this case all the objects are very obviously different so that, for example, a different block cannot be selected for the weight in water to the block used for dry weight. Make sure that each group has a floating object which weighs more than a sinking object.

Other possible objects: plasticine, fruit or vegetables, other metals Avoid: Aluminium foil, paper, foam, things which float because of surface tension, things which soak up water. Notes on materials preparation The object needs to be immersed in water without the forcemeter also being immersed. Objects could have string attached.

Sample results Floating objects:

weight in water 0 N upthrust weight

200 g metal weight: weight 2 N weight in water 1:8 N upthrust 2 1:8 0:2 N



Finding volume

K3a

Resources available Core sheet

l

Finding volume of irregular shaped objects by displacement of water

l

Displacement can large enough to take each object in turn or other container, e.g. plastic beaker. For displacement cans: beakers or measuring cylinders to collect displaced water.

Help sheet (K3ah)

A more detailed approach to finding volume by displacement

l

CD-ROM


For the activity described on the help sheet the same equipment is required. A measuring cylinder per group may also be required, if pupils are to make quantitative measurements of volume.

Links with Book 1

SoW

Sc1

K3

7K page 1

2f, g, k, m, p

For other containers: Some way of collecting displaced water, e.g. a larger tray, beaker or bowl, a funnel and a smaller beaker.

Safety Use plastic containers rather than glass.

Activity procedure 1 The principles of floating and sinking and

upthrust are all treated by comparison in these K3 activities. As stated in SoW, pupils will measure density of rocks in Unit 8H. For quantitative measurements of volume, measuring cylinders would be required.

2 Pupils collect the volume of water displaced

by objects when the object is immersed in water. Ideally the objects would be the same as those used in K2.

Running the activity Use objects which sink first as they are much easier. They will get better results with larger objects. If you have very small displacement cans, you will have to decide whether it might be better to use a large beaker so that the errors will be a smaller fraction of the volume. Remind pupils that pushing a floating object under the water has to be done carefully, so as not to measure the volume of their hand as well. Remind pupils to top up the displacement container before each object is tested.

Materials required Per group l Set of objects as used in Activity K2 (some float, some sink). 5 q I Bradley, C Tear, M Winterbottom, S Young, 2001, The Heinemann Science Scheme


Finding the weight of water Resources available Core sheet

CD-ROM

Measure the weight of water displaced by objects when immersed. All text customisable

Links with Book 1

SoW

Sc1

K3

7K page 1

2f, g, k, m, p

Safety Ensure mains switches and plug top transformers used for electric balances are not handled with wet hands or splashed with water. Use plastic containers rather than glass.

Activity procedure Using scales 1 Pupils try balancing the weight of water displaced by an object against the weight of the object itself.

2 If they have not spilled the water, the floating

objects should be lighter than the water and the sinking objects should be heavier than the water.

K3b

will give the largest difference in weight ± so that even if some water has been spilled the results should still be clear. As with K3a, larger objects should mean errors have less impact.

Materials required Per group l Scales or electronic balance. l

Set of objects as used in Activity K2 (some float, some sink).

l

Displacement can large enough to take each object in turn or other container, e.g. plastic beaker.

l

For displacement cans: beakers or measuring cylinders to collect displaced water.

l

For other containers: some way of collecting displaced water eg a larger tray, beaker or bowl, a funnel and a smaller beaker.

Sample results In analysing the results: 1 Metal. 2 Air-filled plastic, maybe wood. 3 Yes or no (depends on objects). 4 Maybe wood, solid plastic.

Using an electronic balance

1 This introduces the extra stage of writing down the weight in each case.

2 Pupils weigh the water and weigh the object

and then compare the weights to see which is larger ± not as visual, but good practice with weighing.

As an extension activity for a dextrous group which finishes early you may like to challenge them to find out what happens if they compare the water displaced by a floating object (i.e. don't immerse it) with the weight of the object. In every case the weights should be equal, but this will require careful measurement, and use of a large object, preferably one which floats low in the water so that there is a reasonable amount of displaced water to measure.

Running the activity Metal weights and air filled plastic toys (if airtight) should give best results, because they 6 q I Bradley, C Tear, M Winterbottom, S Young, 2001, The Heinemann Science Scheme


Boats and ships

K3b Extension

Resources available

Sample results

Extension sheet

Investigating floating of boats and ships

CD-ROM


Links with Book 1

SoW

Sc1

K3

7K page 1

2g, h, k, l, m

The tub should go down a few cm into the water. When 200 g of water is poured into the tub the level should be the same as the pen mark ± in other words the water displaced weighed 200 g in order to float the 200 g weight. If the tub is put back in the water it should float so that the water level inside and outside the boat are the same.

Answers

Safety Ensure mains switches and plug top transformers used for electric balances are not handled with wet hands or splashed with water.

Activity procedure Pupils float a plastic tub as a simple `boat' and load it with a 200 g weight to see that it floats lower in the water. They then compare the water displaced with the weight. This activity requires only kitchen scales and weights, and it may be possible for some pupils to do this at home, or to do at school outside normal lesson time.

Running the activity The tub should be light, so that it displaces practically no water by itself. The sides should be deep enough that it doesn't sink when the weight is added ± a weight of at least 200 g is needed to give a nice clear result. Adding the weight so that the tub does not tip over requires some care. A waterproof pen helps with marking the water level. When they weigh out 200 g of water ± and see how much water the weight needs to displace in order to float ± it really helps to make the whole concept clear.

1 The steel ship has air inside it. It is able to displace a much larger volume of water than its own volume. This means it can displace its own weight of water, so that the upthrust is enough to hold it up. 2 a The wooden boat will still float at the surface even if it is full of water. b The steel boat will sink to the bottom if it fills with water. 3 a They calculated that if one section was holed and filled with water, the ship would still displace more than its own weight of water and would not sink. b Because the iceberg ripped through lots of sections, too much of the ship filled with water and it could no longer displace its own weight of water.

Materials required l

A light plastic container such as a 1 kg margarine tub, with deep sides.

l

A 200 g weight.

l

A bowl or sink of water to float the tub in.

l

A waterproof pen, for marking the water level on the tub.

l

Scales or balance to weigh out 200 g of water 7 q I Bradley, C Tear, M Winterbottom, S Young, 2001, The Heinemann Science Scheme


Stretching a spring Resources available Core sheet 6a

Stretching a spring

Extension sheet 6b

Stretching a rubber band

Help sheet 6abh

Plotting force ± extension graphs

CD-ROM


Links with Book 1

SoW

Sc1

K6

7K page 2

2e±i

Safety Eye protection should be worn when stretching elastic materials in case they snap and flick back into the eyes. A container of sand, or a box full of crumpled paper to catch the weights, will prevent fingers, hands and feet from being underneath, if weights do drop suddenly. It will also help with reducing damage to surfaces and noise levels. Ensure that in the excitement of the experiment the container does not get moved to one side.

Activity procedure 1 Before the experiment determine the

maximum safe weight which can be added to the spring without permanently stretching it.

2 Allow a margin of error and write on the worksheet (or ask pupils to do so) the maximum weight they should add to the spring.

3 Pupils should set up a retort stand, boss and

clamp to hold the spring and a metre ruler. They will need to use a set square to read off the ruler level with the bottom of the spring, or to attach a small pointer such as a twist of wire. They will add weights one by one and record the ruler readings, from which they can calculate the extension.

K6a Core may be possible to plot the actual values of extension and not use a scale.

Running the activity The ruler needs to be vertical and the correct way up so that the measurement increases as the spring extends. The spring needs to hang vertically. The weights should be positioned over a beaker or bucket of sand (depending on size of weights used) to ensure that the weights have a soft landing if dropped and do not land on a foot or hand. If pupils can plot the graph before dismantling the apparatus they can check any readings which do not fall on the line, but time may not permit this. Plotting the graph Make sure that the extension being plotted is not magnified by the scale of the graph. (If the springs produce only very small extensions you may need to find some alternative springs to produce extensions of a cm or a few cm for each weight added in order to produce a reasonable graph without large errors.)

Materials required Per group l Retort stand, boss, clamp, metre ruler. l Method for reading ruler, e.g. set square, or a twist of wire such as a food bag tie which can be attached to the bottom of the spring. l Container of sand for weights to land in. l Spring and set of weights: you will almost certainly have a set of springs for this experiment. Select the appropriate range of weights for the spring (try the maximum and minimum weight, and the extension when one weight is added). For best results you need an extension of 2 or 3 cm for each weight. Do not give a group of pupils more weights than the safe total you have allowed for the experiment.

Plotting the graph They plot a line graph of force in newtons against extension in cm or mm as appropriate. It 8 q I Bradley, C Tear, M Winterbottom, S Young, 2001, The Heinemann Science Scheme


Stretching a rubber band Resources available

K6b Extension Running the activity

Extension 6b

Stretching a rubber band

Help sheet K6a/b

Analysing results

CD-ROM


If pupils can plot the graph before dismantling the apparatus they can check any readings which do not fall on the line, but time may not permit this.

Links with Book 1

SoW

Sc1

K6

7K page 2

1b, 2a±p

The ruler needs to be vertical and the correct way up so that the measurement increases as the spring extends. The band needs to hang vertically. The weights should be positioned over a beaker or bucket of sand.

Safety Eye protection should be worn when stretching elastic materials in case they snap and flick back into the eyes.

Activity procedure 1 Before the experiment determine the

maximum safe weight which can be added to the rubber band without permanently stretching it. Allow a margin of error and write on the worksheet (or ask pupils to do so) the maximum weight they should add to the rubber band.

2 Pupils should set up a retort stand, boss and

clamp to hold the rubber band and a metre ruler. They will need to use a set square to read off the ruler level with the bottom of the spring, or to attach a small pointer such as a twist of wire. They will add weights one by one and record the ruler readings, from which they can calculate the extension.

They may notice that the first weights added do not seem to produce a change in length. If they remove the weights and write down the readings fairly quickly they should clearly see that the band is longer now than it was with the same weight when being extended. Take care that they don't decide to copy the original results because they are so sure there will be no difference. (The alignment of the long chains of molecules in the rubber/plastic takes time to disappear when the force is removed.) Plotting the graph Make sure that the extension being plotted is not magnified by the scale of the graph. (If the bands produce only very small extensions you may need to find some alternative bands to produce extensions of a cm or a few cm for each weight added in order to produce a reasonable graph without large errors.)

Materials required Per group l Retort stand, boss, clamp, metre ruler. l

Method for reading ruler, e.g. set square, or a twist of wire such as a food bag tie which can be attached to the bottom of the spring

l

Container of sand for weights to land in.

l

Rubber/elastic bands and set of weights: select the bands by trying maximum and minimum weight and checking extension for one weight. Do not give a group of pupils more weights than the safe total you have allowed for the experiment.

3 Pupils may have difficulty measuring the

band with no weights on it. They may need some help in deciding what to do ± perhaps start with a weight on the band and not measure the zero extension. They will probably need encouraging to remove the weights one at a time and take each measurement again because they will expect the results to be the same.

Plotting the graph They plot a line graph of force in newtons against extension in cm or mm as appropriate. It may be possible to plot the actual values of extension and not use a scale.

Sample results A larger band and set of larger weights may be easier for pupils to work with, but even a small band gives these results: 9



Stretching a rubber band continued

K6b Extension

Mass (g)

Weight (N)

Ruler reading (mm)

Extension from 0.5 N (mm)

50

0.5

224

0

90

0.9

227

3

120

1.2

228

4

160

1.6

232

8

200

2

237

13

240

2.4

242

18

200

2

238

14

160

1.6

232

8

120

1.2

230

6

90

0.9

227

3

50

0.5

224

0


Activity

Why do things float?

K2 Core

Aim When you push floating objects down in the water there is a force pushing them up again. This force is called upthrust. In this activity we are going to measure it.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

Equipment l newtonmeter l different objects l container of water

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

not above the surface

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

not touching the bottom

Preparing Look at the objects. Write down your prediction about the readings you will get when you measure the weight of objects, and their weight when they are in water. Draw a table with four columns: Name of object

Weight of object out of water (N)

Weight of object in water (N)

Upthrust (N)

What to do 1 Carefully weigh an object, in air and then when it is in the water. 2 Record the readings in your table. 3 Work out the upthrust and record it in the table. 4 Repeat for all the other objects. Analysing 1 What do you notice about the weight in the water for objects that are floating? 2 What do you notice about the other weights? 3 Write a conclusion for your experiment describing what it shows us about upthrust. Evaluating 1 Were your predictions correct? 2 If not, why do you think your results were different to the ones you expected? 11 q I Bradley, C Tear, M Winterbottom, S Young, 2001, The Heinemann Science Scheme

Activity

Finding volume

K3a Core

Aim If something has an irregular shape it is 200 not easy to work out its volume. This round metal object has a weight of 200 g. But how can we find its volume? One way is to put it in a displacement can, or Eureka beaker, and collect the water that overflows. This is called the displaced water.

200

Preparing If you don't have a special can, any container will do, as long as it is full to the brim of water. Think about how you are going to collect the water which spills over the edge. Decide how you are going to record your results. Equipment l l

beaker different objects

l l

measuring cylinder tray

What to do 1 Fill your can carefully to the brim with water. 2 Lower an object in carefully and collect the water which spills over the edge. 3 Record your results, then repeat using other objects. Analysing 1 How can you work out from the displaced water what the volume of each object is? 2 Work out the volume of each object. 3 Some objects do not sink. How did you measure their volume? Evaluating 1 Are you sure you collected all the displaced water? 2 You probably had to push floating objects down into the water? How might this affect your result? 12 q I Bradley, C Tear, M Winterbottom, S Young, 2001, The Heinemann Science Scheme

Activity

Finding the weight of water

K3b Core

Aim You have measured the volume of water displaced by an object. Now you are going to measure how much this displaced water weighs. Equipment l l

beaker of water scales/electronic balance

l

different objects

What to do 1 Find the weight of displaced water from all or some of your objects using one of the methods shown below. 2 Draw a table for your results: Object

Which was heavier? object

water displaced

Does the object float or sink? it floats

it sinks

Scales: 3 Put the beaker of water on one scale pan and add the object. Remove the beaker or displacement can, without spilling any more water (why is this important?) 4 Put the object on the other scale pan to see which is heavier: the object or the water it has displaced? Electronic balance: 5 Weigh the beaker of displaced water. 6 Now dry the beaker and the object and weigh them. 7 Which is heavier: the beaker with the object or the beaker with the water the object displaced? Analysing 1 Some objects were much heavier than the water they displaced. Form which materials were these objects made? 2 Some objects were much lighter than the water they displaced. What were they made of? 3 Did you find any objects which weighed almost the same as the water they displaced? 4 What were they made of? Evaluating Which volume measurements were most difficult to measure accurately? (For example: Floating or sinking objects? Large or small objects?) 13 q I Bradley, C Tear, M Winterbottom, S Young, 2001, The Heinemann Science Scheme

Activity

Measuring the volume of an object The volume of something is the amount of space it takes up. We can't always squash the object we want to measure into a cube shape. This is how we can work out the volume of something with an odd shape.

K3a Help

2 cm

A cube of plasticine with sides of 2 cm has volume 2 2 2 8 cm3

Equipment l plasticine l eureka beaker l measuring cylinder

You can make it into a different shape ± but its volume is not changed

What to do 1 Fill a can to the brim with water. 2 Put the object in gently. 3 Make sure the object is completely covered in water. 4 Don't put your fingers in to move it around. 5 Collect the water that overflowed ± this water has the same volume as the object. These cans shown below are Eureka beakers or displacement cans. The spout makes it easier to collect the water. Which of these cans will give the correct volume?

A

B

C

D

Questions 1 Why must the can be full to the brim? 2 Why must you put the object in carefully?

4 What would happen to the amount of water you collect if you put your fingers in as well?

3 Why does the object need to be completely covered?

5 How would putting your fingers in affect your result?


Activity

Boats and ships

K3b Extension

Aim To investigate floating ships and boats. Equipment l

empty (clean) margarine tub or other food container with fairly steep sides e.g. a 1 kg rectangular margarine tub

l

200 g weight

l

sink or bowl full of water to float it in

What to do 1 Float the tub in the water. It is very light ± notice how it floats on the surface. 2 Put the weight carefully in the centre so that the tub doesn't tip. What happens? 3 Mark the level of the water on the outside of the tub with a pen. 4 Take the tub out of the water. 5 Now weigh out 200 g of water (remember to allow for the weight of the container). 6 Tip this water into your empty tub. What do you notice about the level of the water inside the tub, compared to the level you marked outside the tub? 7 Try floating the tub of water in the bowl of water. What happens? Questions 1 A block of steel will sink, but a ship made of steel will float. Explain why a steel ship doesn't sink. 2 A ship of wood and a ship of steel both float. If they take in a lot of water what will happen (a) to the wooden boat? (b) to the steel boat? 3 The makers of the Titanic thought she was unsinkable because the hull was divided into sections like this:

a Explain how this would make a ship more difficult to sink. b The iceberg that sunk the ship ripped through several sections. Why did this cause the ship to sink?


Activity

Stretching a spring

K6a Core

Aim To find out how a spring stretches as the force on it increases.

Wear eye protection in case the spring snaps.

0

Equipment l spring l metre ruler l weights of different amounts l retort stand, boss and clamp l container of sand

1 2 3 4

Extension (mm)

weights 8 9

0

10

0

7

0

Ruler reading (mm)

spring

6

Total weight (N) (100 g 5 1 N)

5

retort stand, boss and clamp

What to do 1 Draw a table like this for your results: Total mass (g)

metre ruler

container of sand 2

3

4 5 6

Set up your experiment as shown in the diagram. Make sure: (a) the ruler is vertical, not leaning at an angle; (b) the spring is hanging twist of vertically. wire making a With no mass on the spring, use pointer the pointer to read off the set square measurement on the ruler for the bottom of the spring, and write it Here are two ways of lining up the bottom of the spring with the ruler to make an accurate in the table. measurement. Add a mass and record the mass and the new ruler reading. Work out the weight and extension and write them in the table. Carry on adding masses, but do not add more than your teacher tells you to. Record all the readings in the table.

Analysing l Plot a graph of weight (in newtons) against extension (in mm). l Describe how you could use your graph to find the weight of an object.


Activity

Stretching a rubber band Aim Plan an experiment to answer the question: Does a rubber band behave in the same way as a spring when it is stretched? Remember l A spring shows equal increases in extension for equal increases in force (weight) l A spring goes back to its original length after stretching (if you haven't stretched it too far) ± you can add more force and take it away over and over again ± you always get the same extension for the same force.

K6b Extension

Wear eye protection in case the band snaps. Put a container of sand or a box containing crumpled paper under the weights to catch them safely if they fall.

Planning l Discuss with your group how to find out whether an elastic band will stretch in the same way as a spring. l What measurements will you need to make? l What equipment will you need to do your experiment? How will it be set up? l How will you make your measurements accurate? l How many times will you repeat your measurements? Results How will you record your results? (Remember to use the right units for weight) Analysing l How will you analyse your results? l What do your results tell you about the way a rubber band stretches? l How will you compare your results for the band with the results for a spring? l What is the difference between the way a spring stretches and the way a rubber band stretches?


Activity

Analysing results (Activities K6a/b)

K6a/b Help

Recording your results 1 Draw a table like this for your results:

1st reading (no weights)

Total mass (g)

Total weight (N) (100 g 5 1 N)

0

0

Ruler reading (mm)

Extension (mm) (Take the extension of the spring or band without weights away from the reading) 0

2nd reading 3rd reading 4th reading

Plotting a graph 1 Plot a graph of the force in newtons against the extension in mm. Force (newtons)

Extension (mm)

2 Your graph needs to start at 0 on both axes. 3 Remember to choose scales so that the largest force and the largest extension will fit on the paper. 4 Remember to label each axis and give your graph a title.

Analysing 1 Can you join the points on your graph with a straight line, or is it a curve? 2 What is the pattern that you have found? 3 Is there a point which doesn't fit in with the others? Why might this be? 4 If your equipment is still set up try checking any results that did not quite fit the pattern. 5 How could you use your equipment to find the weight of an object?


Homework

Forces

K1

1 These forcemeters are being used to measure different forces. What is the size of the force in each case? (Remember force is measured in newtons.)

a Weight of a block b Weight of an apple c Weight of a sack

0

0

0

1

100

2

200

3

300

4

400

1 2 3 4 5 6 7

2 A mass of 1 kg has a weight of 10 N on the Earth. Work out the weights in newtons of:

8 9 10

N

5

N

500

N

a A 50 kg student b A 0.1 kg apple c A 1000 kg rock

3 With the same forcemeter a student measures the weight of an apple and an orange. The same container is used to measure both the fruits and the container itself has a weight. The results are shown on the right.

a Write down the weight in each case. b Work out the weight of the apple. c Work out the weight of the orange.

0

0

0

1

1

1

2

2

2

3

3

3

4

4

4

5

N

5

N

5

N


Homework

Floating and sinking

K2

You will have done some experiments 2 Try to push some floating objects about floating and sinking at primary under water. What happens? school. 3 If the objects now sink, why is this? You may remember the answers to some What has happened? of these questions. Do some experiments 4 If the objects won't sink, why do you at home so that you can answer them all. think they come to the surface? What You may like to do the experiments in a does it feel like when you try to push sink, basin, bowl (it doesn't have to be them under? very big) or when taking a bath. If the 5 What happens to the water level in the weather is good it may be a good idea to bowl when objects sink? (You will not do them outside. be able to see any change in a large Wherever you decide to work, make sure container such as the bath ± unless the that you leave the area tidy and mop up object is also large ± such as a person any spills of water! for example!) 1 Make up a table of objects which float 6 What happens to the water level in the and objects which sink. (Record the bowl when objects float? material the object is made of, e.g. wooden brick, metal coin.) .........................................................................................

"

Homework

Displacement

1. plastic ping pong ball

a

K2

2. metal weight

3. stone

4. rock

b

c

d

These objects were dropped in water and the amount of water displaced by each one was collected in a beaker. Unfortunately the scientist forgot to note

which was which. Can you work out which beaker was collected from which object?


Homework

Density

K3

You have compared lots of different solids with water. Now compare some liquids. This table shows the weight of 1 litre (1000 cm3 ) of different liquids: Look at the table. Which weighs the most: 1 1 litre of milk or 1 litre of cream? 2 1 litre of Atlantic seawater or 1 litre of fresh water? 3 1 litre of oil or 1 litre of water?

Use your answer to explain why cream floats on milk and oil floats on water. 4 How many litres of water would weigh the same as 1 litre of mercury?

Liquid

Weight (in N) of 1 litre of liquid

water

10

oil

8

salt water (Atlantic)

10.3

salt water (Dead Sea)

10.9

cream

9

milk

10.3

mercury

135

5 in a less dense liquid

in water

in a denser liquid

same weight (different liquids)

You have seen that if an object floats in water the water displaced weighs the same as the object. Now we see that the object will float in any liquid if the weight of liquid displaced weighs the same as the object. Draw a diagram of the same boat floating on (a) fresh water, (b) mercury, (c) the Dead Sea. 6 Samuel Plimsoll realised that ships were being deliberately loaded up, insured for lots of money and sent out to parts of the world where they were more likely to sink, so that the ship owners could collect the insurance money.

TF

L

R

T S W WNA

Ships sail in all sorts of different seas, warm and cold, freshwater rivers and salty seas. Some seas are much saltier than others. From the table, choose the type of water to load the ship in, and the type of water to sail to, to make the ship low in the water and more likely to sink. 21 q I Bradley, C Tear, M Winterbottom, S Young, 2001, The Heinemann Science Scheme

Homework

Balanced forces 1 This oil drum has been washed up on a rocky shore.

The forces on it are its weight and the reaction force from the rock which stops it moving downwards. a Copy the diagram. b Draw a diagram of the oil drum floating in the sea and mark the forces on it. c On the next tide the oil drum is washed onto soft mud and it sinks. What can you say about the reaction force when it stops sinking in the mud? d Draw a diagram of the oil drum sunk in the mud, and mark the forces on it. e In some places there are quicksands. Can you explain why the drum would carry on sinking in quicksand? f Draw a diagram of the oil drum sinking in quicksand. Why is this diagram different to all the others? 2 A sky diver jumps from a plane. He is falling.

a What is the name we give to force A? b What is the name we give to force B? c At first force A is much smaller than force B. What will happen to the sky diver? d Eventually forces A and B will be the same. What happens to the sky diver when the forces are equal? e Why does force A change? f The parachute opens. Draw a diagram showing forces A and B now. (Think carefully about which force is larger.) g What will happen to the motion of the sky diver now? h When the sky diver lands, force A will be zero. What is the new force balancing force B? 3 This road sign is sometimes used on bridges and in open countryside.

a Explain what the sign means. b Why do you find the signs on bridges? c What would a motorist need to do?


K4

R

W

A

B

Homework

Friction

K5

Read this information about tyres and stopping cars. Then answer the questions. If there were no friction between the tyre on a car and the road the wheel would not grip the road, it would spin. This is what happens when a car skids. When a car skids the driver cannot steer.

In heavy rain there is a lot of water on the surface of the roads. To stop the car from slipping, car tyres have a tread pattern which helps to clear the water from between the tyre and the road. After several thousands of miles the tread wears away, until eventually the tyre has little pattern left ± we say it is `bald'. If a driver travels at 80 km per hour (about 50 mph) and something happens so that he must stop, this diagram shows how far the car travels before stopping. 16 m

The car travels this distance while the driver is thinking about braking

on dry roads 35 m

The car travels this distance while braking

16 m

The car finally stops here

on wet roads 70 m

1 What would happen if there were no friction between the wheels of a car and the road? 2 At 80 km per hour what is the shortest total distance a car travels before stopping on (a) dry roads, (b) wet roads? 3 Why should people drive more slowly in wet weather? 4 Why do car wheels often spin on icy roads? 5 Why are grit and sand put on roads in winter? 6 Why is it illegal to drive with tyres which have less than 2 mm depth of tread? 7 Racing drivers often use smooth tyres in dry weather, and stop to fit tyres with tread if it is wet. Explain why. 23 q I Bradley, C Tear, M Winterbottom, S Young, 2001, The Heinemann Science Scheme

Homework

Springs and stretchy things

2 Another spring is 5 cm long. When 500 g (5 N) is hung on it, it stretches to 5.5 cm.

a What is the extension in cm? b What will the extension be when 1 kg (10 N) is hung on it? c How long will the spring be when a 10 N weight is hung on it? d When the length of the spring is 7.5 cm, how much weight (in N) is hung on it? (Hint: remember to work out the extension first.) 3 Here is the graph of a spring: Force (newtons) 4

(a) 20

Force (newtons)

a What is the extension in cm? b When a total 250 g mass (a 2.5 N weight) is hung on the spring what will the extension be? c How long is the spring with the 2.5 N weight on it?

4 Here are the graphs for two very different springs:

15

10

5

0

0

1

2

3

4

5

6 7 8 Extension (mm)

0

2

4

6 8 10 Extension (cm)

(b) 1.6 1.4 1.2

Force (newtons)

1 A spring is 3 cm long. When a 100 g mass (a 1 N weight) is hung on it, it stretches to 4 cm.

K6

1.0 0.8 0.6 0.4 0.2

3

0

2 1 0

0

1

2

3

4

5

6

7 8 9 Extension (cm)

Use it to answer these questions. a What is the extension of the spring when a 2 N weight is hung on it? b What weight is needed to make the spring 1 cm longer? c A brick is hung on the spring and extends it by 8 cm. How much does the brick weigh?

a How much does spring (a) extend when 10 N is hung on it? b Work out how much spring (a) would extend when 250 N is hung on it. c How much does spring (b) extend when 1 N is hung on it? d Which spring would be best to make into a forcemeter for measuring 25 kg bags of potatoes? e If the other spring was made into a forcemeter, suggest something you could weigh with it.


Specials

Forces

K1

1 These forcemeters are being used to measure different forces. What is the size of the force in each case? (Remember: force is measured in newtons.)

0

0

0

1

100

2

200

3

300

4

400

1 2 3

a Weight of a block.

4

b Weight of an apple.

6

5

7

c Weight of a sack.

8 9 10

N

5

N

500

N

2 Complete this table: Push

Pull

Twist

Decide if these forces are pushing forces, pulling forces or twisting forces and write them in the correct column: l opening the fridge l closing a drawer l tightening a screw l gravity keeping you on the ground l unlocking the door l kicking a ball l a tug of war l undoing a jar l clicking a mouse


Specials

Floating and sinking

K2

Complete these sentences using the words in the box to fill in the gaps: less

force

float

sinking

upthrust

When an object sinks or is pushed under the water a push it up. We call this force

tries to .

Sometimes the upthrust is large enough to make an object

.

Sometimes the upthrust is not enough to stop the object from , it just makes the object seem to weigh


.

Specials

Displacement

K3

1 Use the words in the box to fill in the gaps: displacement

water

volume

cylinder

To find the of an object put it in a can. The which overflows has the same volume as the object. We can measure the volume of the water using a measuring

.

2 Draw arrows linking the correct statements to the correct diagrams.

When the volume of water displaced weighs less than an object the object

When the volume of water displaced weighs more than the object the

will

object will

(choose from float or sink).

(choose from float or sink).


Specials

Balanced forces These two robots are stuck together. They are not moving.

Force

Each is using a large driving force to try and pull away from the other. 1 Mark an arrow showing the force of Attacker on your diagram. (Remember: the two robots are not moving.) 2 Attacker increases its driving force, but Bludger is already at maximum driving force. What will happen?

3 What force will act to slow the robots down now that

they are moving?

4 Here is a diagram of another robot.

Force

The driving force is shown by an arrow. Add another arrow to show the friction.


K4

Specials

Forces wordsearch

K5

T

H

R

U

S

T

D

R

Q

U

R

S

F

O

R

C

E

M

U

P

F

E

S

K

P

E

E

H

G

N

S

S

S

A

M

X

T

F

R

P

A

G

H

Z

M

A

K

M

S

Y

T

I

V

A

R

G

E

R

S

N

P

A

I

T

B

C

V

I

J

I

L

U

A

U

L

O

U

M

V

O

T

W

A

Y

R

X

L

E

F

A

R

E

L

M

I

C

C

K

J

L

G

R

N

F

N

U

A

O

H

D

S

P

O

G

I

M

E

R

M

T

I

W

T

G

A

O

R

C

W

G

I

E

M

E

A

M

T

L

U

E

T

Q

L

J

E

I

C

N

H

I

S

A

O

I

U

C

D

G

K

R

T

K

N

I

N

T

O

R

E

H

P

A

N

N

N

O

G

Y

F

N

S

T

O

K

E

U

P

I

U

A

D

W

A

L

O

P

E

T

X

Y

S

C

R

V

H

S

U

P

T

H

R

U

S

T

U

D

These are some of the words we use when describing forces. How many can you find in the wordsearch? FORCE UPTHRUST KILOGRAM PUSH SINK ARCHIMEDES

GRAVITY WEIGHT DRAG PULL LITRE THRUST

FRICTION MASS NEWTON FLOAT VOLUME MAGNETISM


Specials

Stretching springs

K6

1 When a spring has weights hung on it then it always stretches following this pattern:

Adding equal weights causes equal increases in length. l An increase in length is called an extension. This graph shows what happens when weights are added to a spring. Use it to answer the questions: l

Force (newtons) 5

4

3

2

1

0

1

2

3

4

5

length of spring when it is not stretched

a What is the extension of the spring when there is no weight on it? b What is the extension when a 1 N weight is hung on it? c What is the extension when 2 N is hung on it? d What is the extension when 4 N is hung on it? e Another 1 N is added, making 5 N altogether, what is the extension now? f From your answers to d and e work out how much the extra 1 N made the spring stretch. g The graph doesn't go up to 8 N but can you work out what the extension would be if it did? 30 q I Bradley, C Tear, M Winterbottom, S Young, 2001, The Heinemann Science Scheme

6 7 Extension (cm)

Extension

Mass and weight

K1

The astronaut has a mass of 70 kg. He has a bag of popcorn which has a mass of 100 g. The weight of the astronaut on Earth is 700 N, this is the force of attraction towards the centre of the Earth. The weight of the popcorn is 1 N, so the popcorn is being pulled down with a force of 1 N. If the astronaut or the popcorn falls off a tall building the force pulls them down. If they are far enough away from the Earth they won't hit the ground but will go on falling round the Earth ± they will be in orbit. Things seem to be weightless, when they are really falling, or in orbit.

If the astronaut and the popcorn go to the Moon the force of gravity pulls them towards the centre of the Moon. On the Moon 1 kg is pulled down with a force of 1.6 N, so the astronaut weighs 112 N ( 70 kg 1:6) and the popcorn weighs 0.16 N ( 0:1 kg 1:6)

;;;;; ;;;;; ;;;;;

Earth


Extension

Mass and weight continued

;;;; ;;;; ;;;;; ;;;;; The mass of the astronaut is still 70 kg and the mass of the popcorn is still 100 g. It is only their weight which has changed. Out in space there will be places so far from planets or stars that there will be no gravity in any direction. If the astronaut and the popcorn were at one of these places they would be really weightless. Of course they still have the same masses ± 70 kg and 100 g. All the planets in our solar system have different values for the pull of gravity. On Mars 1 kg weighs 3.8 N so the astronaut weighs 266 N ( 70 kg 3:8) and the popcorn weighs 0.38 N (0:1 kg 3:8)

;;; ;;; ;;; ;;;

1 An astronaut has a mass of 120 kg with spacesuit on. If 1 kg weighs 10 N on the Earth, 1.6 N on the Moon and 3.8 N on Mars, what is his weight in newtons:

a on the Earth? b on the Moon? c on Mars? 2 A Lunar landing module has a mass of 1000 kg. Work out: a its weight on the Earth

b its mass on the Moon c its weight on the Moon.


K1

Extension

Resultant forces

K5

All these tractors are pulling in different directions with different forces. What will happen? You can guess that the forces will combine together and the trailer will move in the direction of the combined pull. It is as if we could replace the forces with one force which has the same effect:

If the forces are in line, we don't have to take the angles into account: Example driving force front wheel

friction

driving force front wheel

friction

The four forces on this two-wheel drive vehicle can be combined to give one force. Work out the size and direction of the total force in each of these cases: 1 200 N 50 N 100 N

40 N

2 3

5N

1N

3N

7N

210 N

320 N

70 N 33 q I Bradley, C Tear, M Winterbottom, S Young, 2001, The Heinemann Science Scheme

Test yourself

Forces and their effects

Unit K

Forces 1

a put an arrow to show the force of friction on the car and label it `friction'. b put an arrow to show the weight of the car and label it `weight' c put an arrow to show the driving force of the car and label it `driving force' d draw an arrow upwards equal and opposite to the weight and label it `reaction force' e What would happen if the reaction force was less than the weight? f Is it possible for the reaction force to be more than the weight? 2

Match these descriptions to the diagrams: car going faster, car slowing down, car travelling at steady speed 3 Choose the correct words to fill in the spaces:

An astronaut on the Moon has the same different

. When the Moon buggy is driving across the

surface there will be no

but

slowing it down but because there is no air.


Test yourself

Forces and their effects continued 4 Label the forces arrows with the names of the forces. In saltier water the child in the ring will: a sink lower in the water b stay the same c not sink as far in the water

Unit K

A

B

5 Cross out the incorrect words so that this writing makes sense:

When a weight is hung on a spring the force/mass/friction makes the spring stretch. If you double the weight on the spring the extension of the spring is halved/doubled/squared. When you remove the weight the spring length of the spring stays the same/goes back to its original length/gets shorter but is still longer than the original length provided you have not overstretched it. This is why springs can be used to measure force/mass/length. 6 Fill in the words to find out the name of the car that went faster than the speed of sound: 1 2 3 4 5 6 7

! 1 2 3 4 5 6 7

The unit of force What happens to an elastic material when a weight is hung on to it A force which slows things down A force which makes things float A force can make moving objects The force of gravity on your mass 2 times the force on a spring gives how many times the extension

7 Draw a ring around all the situations where very little or no friction is wanted. Underline all the situations where high friction is needed.

car brake pads ice skates inside of a frying pan side of a matchbox for lighting the match floor tiles rock climbing boots playground slide

ski slope


End of unit test


Unit K Tier 2±5

9

8

7

6

10

5

4

3

2

1

0

N

1 Some children are doing an experiment to see which surface has best grip. They are using a shoe and pulling it across the surface with a forcemeter. When the shoe starts to move they record the reading on a forcemeter.

The forcemeter registers a reading of 2 units. Here is a table of their results: Surface

Force (N)

wood

2

metal

2

plastic floor tiles

3

teflon

1

a What is the name of the unit that force is measured in? (1 mark) b Name the force that stops the trainer from sliding. (1 mark)

c How will the children decide from results which is the best surface to stop slipping? (1 mark) d Which surface offers the lowest grip? (1 mark) e What do you think would happen to the readings if these materials were spread on the surface? i water (1 mark) ii sand (1 mark)

2 A

B

C

a Which of these diagrams, A, B or C shows what happens when the crate is loaded on the boat? (1 mark) This boat travels around the world to a port where the sea is much saltier, but about the same temperature. b Which of these diagrams, D, E or F shows the boat when it arrives? (1 mark)

D

E

F

The child throws the anchor into the water.


c What is the name of the downward force on the boat? (1 mark) d What happens to this force? (1 mark) e What is the name of the upward force on the boat? (1 mark) f What happens to this force? (1 mark) g Explain your answer. (1 mark)

End of unit test

Forces and their effects continued

Unit K Tier 2±5

3 This chart shows how long it takes for these toys to cross from one side of a hall to the other. Time a How many seconds (seconds) did the car take to 45 cross the hall? 40 (1 mark)

b Which of the toys is the fastest? (1 mark) c Explain how you chose the fastest toy. (1 mark)

35 30 25 20 15 10 5 0

car

spider

beetle fire engine Toy

train

truck

d Copy and complete this formula for calculating the speed: Average speed

time (1 mark)

The car didn't go as fast as expected. It was making a squeaking noise. e How might you be able to make it go faster? (1 mark) 4 This graph shows how much a spring extends in length when weights are hung on it. Force (newtons) 0.5 0.4 0.3 0.2 0.1 0

1

2

3

4

5

6

7

8 Extension (cm)

a Copy and complete this description: doubling the force on the spring

. (1 mark)

b A parcel was hung on the spring and it extended by 6 cm. What was the weight of the parcel? (1 mark)


End of unit test


Unit K Tier 3±6

1 Some children are sliding down a garden slide. They have a hosepipe to run water down the slide and a plastic sheet at the bottom. They are squirting soap on the slide before sliding down. It is not fair you didn’t put enough soap on for my turn – that’s why you went further

That’s not true. Lots of things affect how far you go

Weight

Apart from the amount of soap, name two other things which might affect how far each child travels along the plastic sheet. (2 marks) 2 A

B

C

a Which of these diagrams, A, B or C, shows what happens when the crate is loaded on the boat? (1 mark) This boat travels around the world to a port where the sea is much saltier, but about the same temperature. b Which of these diagrams, D, E or F, shows the boat when it arrives? (1 mark)

D

E

F

The child throws the anchor into the water.


c What happens to the total weight of the boat? (1 mark) d What happens to the upthrust on the boat? (1 mark) e Explain your answer. (1 mark)

End of unit test


Unit K Tier 3±6

3

This parachutist weighs 700 N. After jumping from an aeroplane the parachutist falls faster and faster. a Which of these is true? (1 mark) A The air resistance is greater than 700 N. B The air resistance equals 700 N. C The air resistance is less than 700 N. The parachutist opens the parachute and begins to slow down. b What happens to the weight of the parachutist? (1 mark) c What happens to the air resistance? (1 mark)

30

parachute opened

Speed in m/s

25 20 15 10 X

5 0

25

50

75 100 Time in seconds

125

This graph shows what happens to the speed of the parachutist after the parachute is opened. d Explain why the line is horizontal between 25 s and 125 s in terms of the forces on the parachutist. (1 mark) e What happens at time X? (1 mark) A heavy crate of supplies also needs dropping by parachute. It weighs 1500 N and hits the ground so fast the contents are damaged. f If the crate and parachutist leave the plane together, which will reach the ground first? (1 mark) g How could the parachute be changed to give more air resistance? (1 mark) 39 q I Bradley, C Tear, M Winterbottom, S Young, 2001, The Heinemann Science Scheme

End of unit test

Forces and their effects continued 4 This graph shows how much a spring extends in length when weights are hung on it. Force (newtons) 0.5 0.4 0.3 0.2 0.1 0

1

2

3

4

5

6

7

8 Extension (cm)

a Complete this description: doubling the force on the spring

. (1 mark)

b A parcel was hung on the spring and it extended by 6 cm. What was the weight of the parcel? (1 mark) A bunjee jumper jumps from a cliff top with a stretchy cable attached. The cable is 100 m long and a 1 N force extends the cable by 1 cm. The bungee jumper has a mass of 80 kg. c What is the weight of the jumper? (1 mark) d Work out how much the cable would stretch if the jumper was hung on the end of it? (1 mark) e Work out the new length of the stretched cable. (1 mark) f If a 80 kg astronaut was hung from the cable on the Moon what would happen? (1 mark) A The astronaut would float about as things are weightless. B The astronaut would hang down, but the cable wouldn't stretch. C The astronaut would hang down and the cable would stretch but not as much as on Earth. D The astronaut would hang down and the cable would stretch more than on Earth. E The astronaut would hang down and the cable would stretch the same amount as on the Earth.


Unit K Tier 3±6

Mark scheme


Unit K Tier 2±5

Question

Part

Answer

Mark

Level

1

a

Newton

1

2

b

Friction

1

2

c

The one which takes the most force to make the trainer slide

1

4

d

Teflon

1

3

e i e ii

Readings would all be less Readings would all be more

1 1

3 3

a

A

1

3

b

E

1

4

c

Weight (accept gravity)

1

3

d

It gets less/smaller

1

3

e

Upthrust

1

4

f


1

5

g

The upthrust (accept force) needed to balance weight of boat is less

1

5

a

23 seconds (allow 22s±24s)

1

4

b

Beetle

1

4

c

Shortest bar is the shortest time to cover Distance fastest speed

1

4

d

Distance divided by

1

4

e

Oil/lubrication to reduce friction

1

4

a

Doubles extension (not length)

1

4

b

0.3 N

1

4

2

3

4

Scores in the range of:

Level

3±5

2

6±10

3

11±14

4

15±20

5


Mark scheme


Unit K Tier 3±6

Question

Part

Answer

Mark

Level

1

a

Weight of child Size of child /amount of water/swimsuit material

1 1

4 4

2

a

A

1

3

b

E

1

4

c


1

3

d


1

5

e

The upthrust (accept force) needed to balance weight of boat is less

1

5

a

C

1

4

b

Nothing/weight doesn't change

1

5

c

Increases

1

5

d

The parachutist is travelling at constant speed because the air resistance is the same as his/her weight or forces on him/her are balanced or air resistance 700 N. Must mention operation of forces in some form for credit.

1

6

e

Parachutist lands

1

5

f

Crate lands first

1

4

g

Larger canopy/parachute

1

4

a

Doubles extension (not length)

1

4

b

0.3 N

1

4

c

800 N

1

5

d

800 cm/8 m

1

5

e

108 m

1

5

f

C

1

6

3

4

Scores in the range of:

Level

4±7

3

8±11

4

12±14

5

15±20

6


Student record sheet


Unit K

I can do this very well

I can do this quite well

I need to do more work on this

I know how to identify and measure forces I know that there is an upward force on objects in water and that this force is called upthrust I can explain why some objects float and some sink in water I can explain why objects may float in sea water but sink in fresh water I can identify situations where forces are balanced, or unbalanced I know how to show the size and direction of forces on diagrams I can collect data from an experiment and plot the data as a line graph I can use a graph to make predictions I can use a graph to spot anomalous results (eg mistakes in readings) I can draw a line of best fit I can explain the difference between mass and weight I know which units to use to measure mass and weight I can explain what friction is I can describe how friction can be reduced I can describe situations where friction is helpful I can explain why friction is important in the movement of vehicles I know about speed and the units of speed I know how to interpret distance/time graphs

What I enjoyed most in this unit was

The most useful thing I have learned in this unit was

I need to do more work on


Key words

Unit K Forces and their effects Key word list air resistance attract density displacement

extension friction gravity lubrication

magnetic attraction mass newton upthrust

volume weight

"

.........................................................................................

Glossary

Unit K Forces and their effects Glossary air resistance

force acting against movement in air

gravity

attraction of any mass to any other mass

attract

pull towards

lubrication

density

a measure of how much mass is in a volume

putting a substance between two surfaces to reduce friction

displacement

the amount of liquid or gas moved out of the way by a solid floating or immersed in it

magnetic attraction

north and south poles pulling towards each other

mass

how much material you have

newton

unit of force

extension

how much longer a material becomes when stretched

upthrust

force of water or other liquid/ gas pushing an object upwards

friction

force acting against movement when two surfaces touch

volume

a space

weight

the force of gravity on a mass


Teacher notes and answers


Unit K

Weight of water: sink, float, arrows to appropriate diagrams.

K1 Homework 1 a b c 2 a b c 3 a b c

5.3 N 1.2 N 240 N 500 N 1N 10 000 N Weights 1.6 N, 1.8 N, 3.0 N 1.2 N (hanger 0:4 N) 1.4 N

Boats and ships: see diagrams, scales show steel ship and water displaced by ship.

K4 Homework 1 a Oil drum with equal weight and reaction. b Oil drum floating. Equal weight and upthrust. c Reaction force is equal to weight when it stops sinking. d Oil drum equal weight and reaction. e Reaction force never enough to balance weight. f Oil drum with weight and smaller reaction force. Only diagram where forces not balanced.

K1 Special 1 a 5N b 1.5 N c 200 N 2 Push: drawer, ball, mouse. Pull: fridge, gravity, tug of war. Twist: screw, unlocking door, jar.

K2 Homework ± Floating and sinking This homework is for use before the activity K2. 1 2 3 4 5 6

Table varies. Try to bob up, or sink. Fills with water. Seems to be a force pushing them up. The water level rises. The water level rises.

2a

3b

A air resistance. B weight. Speeds up. Falls with constant speed. Air resistance increases with speed. Force A is much larger than B. Slows down. Reaction force from ground.

3 a Sidewinds (highway code description) or crosswinds. b Wind blowing across the water. c Steer slightly towards the wind to balance the force and keep car going straight.

K2 Homework ± Displacement 1d

2 a b c d e f g h

4c

K4 Special

K2 Special Force, upthrust, float, sinking, less.

K3 Homework 1 2 3 4 5

Milk Seawater Water 13.5 litres Boat (b) much higher in liquid than (a), boat (c) slightly higher than (a). 6 Load in Dead Sea and sail to fresh water. 7 Saltwater line is the lower, freshwater is higher.

K3 Special Volume of water: volume, displacement, water, cylinder.

1 Two equal and opposite forces. 2 Robots will start to move in direction of Attacker. 3 Friction. 4 Friction opposite to driving force and less or equal ± not larger.

K5 Homework 1 2 3 4 5

Wheels spin. a 51 m b 86 m It takes longer to stop ± car travels further. Friction is lower. Increase friction (they also spread salt to melt ice). 6 Because you are more likely to skid, so law brought in for safety. 45


Teacher notes and answers


Unit K

7 Cars will go faster in dry weather with smooth tyres, but they will be unsafe in wet weather.

K1 Extension

K5 Special

1 That mass never changes in value (of course if the popcorn is eaten that is a different matter!)

(wordsearch)

Mass and weight The key issues are:

K6 Homework

2 Weight is different on each planet/star.

1 a 1 cm b 2.5 cm c 5.5 cm 2 a 0.5 cm b 1.0 cm c 6 cm d 25 N 3 a 4 cm b 0.5 cm c 4N 4 a 4 mm b 10 cm c 10 cm d Spring a e Answers vary: things which weigh between 0.01 N and 10 N and/or where the weight is required to 0.01 N (mass of 1 g).

When things are falling or in orbit they appear to be weightless, but try to avoid reinforcing the idea that they are weightless. If there were no force on them they would not be in orbit, or falling. BBC Science in Action Video 3: Gravity (20 mins) shows this very well.

K6 Special a 0 cm e 5 cm

b 1 cm f 1 cm

c 2 cm g 8 cm

d 4 cm

Additional resources The BBC Science in Action Video 3 has 6, 20 min programmes. The first two are on electricity. 3. Forces: deals with balanced forces. 4. Gravity: weight, gravity and mass and weight. 5. Friction: friction and air resistance. 6. Linear motion: good treatment of speed.

When objects are far from the influence of planets or stars then there is no measurable force on them and they are weightless. 1 a a b 2 a c d

1200 N 192 N 456 N 10 000 N 1000 kg 1600 N

K2 Extension Resultant forces 1 210 N left 2 0N 3 20 N right


Help with navigation Use the bookmarks on the left of the screen to look at the different activities and teacher’s notes – click on a title to view the first page of that section; click on the plus sign (+) to the left of a title to view a list of activities (or other pages) in that section; then click on any of these subtitles to view that page (or part of a page). You can also use the scroll bar (down the right side of the screen) to scroll down through the pages, or you can click on the

Previous Page and

Next Page buttons to flick through the document page by page.

Help with printing From the File menu, select Print. The Print dialogue box is displayed on screen. To print the whole of the document – i.e. scheme of work, teacher and technician notes, activities, homework, specials, extension, test yourself, end of unit test, mark scheme, key words and glossary – select All 47 pages in the Print Range section. Then click on: OK. To print a specific section for this unit, select Pages from in the Print Range section and then key in the following in the from: or to: boxes:

Scheme of work Teacher and technician notes Activities Homework Specials Extension Test yourself End of unit test Mark scheme Student record sheet Key words and glossary Teacher notes and answers

in the from: box 2 4 11 19 25 31 34 36 41 43 44 45

in the to: box 3 10 18 24 30 33 35 40 42 43 44 46