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STUDENT HOMEWORK BOOKLET

NAME:

CLASS:

TEACHER:

This homework booklet has been seen and checked by ___________________________[Parent / Guardian]

This homework booklet has been marked by ____________________________________[Teacher]

9K Word Sheets9Ka – The need for speed

Word Pronunciation Meaningmean speed The total distance something travels divided by

the total time taken allows you to calculate the thing’s mean or average speed.

speed How fast something is moving. Often measured in metres per second (m/s), miles per hour (mph) or kilometres per hour (km/h).

9Kb – Faster and faster

Word Pronunciation Meaningaccelerate ack-sell-er-ate Change speed.air resistance A force that tries to slow down things that are

moving through the air. It is a type of friction.balanced forces When two forces are the same strength, but

working in opposite directions.friction A force that tries to slow things down when two

things rub against each other.unbalanced forces When two forces working in opposite directions

are not the same strength.

9Kc – Drag act

Word Pronunciation Meaningdrag Another name for air resistance or water

resistance.streamlined Giving something a smooth shape to reduce the

air resistance or water resistance.water resistance A force that tries to slow down things that are

moving through water. It is a type of friction.

9Kd – Hitting the limit

Word Pronunciation Meaningdistance–time graph

A graph that shows how far something has moved in a certain time.

terminal velocity The maximum speed of an object. Usually only applies to falling objects when the downward force is balanced by drag.

Smithdon High School 2

QUESTION 1

(a) Megan’s dog is pulling on his lead. Which arrow, A, B, C or D, shows the direction of this force? Give the letter.

................................1 mark

(b) Megan has to pull to keep the dog still. Which arrow shows the direction of this force? Give the letter.

................................1 mark

(c) Suddenly the dog’s collar breaks.

(i) When the collar breaks, the lead moves.Draw an arrow on the diagram to show which way the lead starts to move.

1 mark

(ii) Why does the lead move when the collar breaks?

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


..................................................................................................1 mark

Maximum 4 marksQUESTION 2

Five people take it in turns to sit on a see-saw. The table gives the weight of each person.

person weight, in N

Jack 510

Ellie 540

Rosie 490

Maggy 540

Andy 560

(a) Andy sits at one end, but there is nobody on the other end.

Andy sits on the see-saw. In which direction does his end of the see-saw move?

...................................................................1 mark

(b) Which two people in the table above could make the see-saw balance?

………………………..……...…......and………………….......………….1 mark

Use information in the table to help you answer parts (c) and (d).

(c) Rosie sits on end A, and Jack sits on end B.


They lift their feet.What happens to each end of the see-saw?Write up or down in the boxes under Rosie and Jack.

1 mark

(d) Ellie sits on end A, and another of the group sits on end B.Ellie's end stays down.

Who could be on end B?

...................................................................1 mark

Maximum 4 marks

QUESTION 3

Joe saw two types of swing in the park.


He noticed that the time for one complete swing, forward and back, was different for the two types of swing.

He did not know whether the length of the chains or the mass of the person affected the time for one complete swing.

He made model swings and measured how long it took for 10 complete swings in 4 investigations.

string

p lastic inem ass

Here are his results.

investigationA B C D

length of string, in cm 25 25 50 75

mass of plasticine, in g 100 50 100 100

time for 10 complete swings, in s 10.0 10.0 14.2 17.4


Here is Joe's conclusion:

C hanging the m ass of the p lastic inehas no effect on the tim e takenfor 10 com ple te sw ings.

(a) Which two of his investigations, A, B, C or D, provided evidence to support his conclusion?

………………….. and …………………….1 mark

(b) Look at the results table.

(i) Describe how the length of the string affects the time for 10 complete swings.

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

..................................................................................................1 mark

(ii) Which three of his investigations are best evidence for this?

………………….. and …………………….and …………………1 mark

(c) Use his previous table of results to predict the times for 10 complete swings in two further investigations, E and F.Write your answers in the table below.

investigationE F

length of string, in cm 25 100

mass of plasticine, in g 25 100

time for 10 complete swings, in s ................ ................

1 mark

Maximum 4 marks


QUESTION 4

pu ll o fengine

(a) A railway engine is being used to try to pull a wagon along a level track. The wagon’s brakes are on, and the wagon does not move.

(i) Draw one arrow on the diagram to show the direction of the force which prevents the wagon from moving.

1 mark

(ii) Is the force which prevents the wagon from moving greater than, equal to or less than the pull of the engine?

.................................................................................................. 1 mark

(b) (i) When the wagon’s brakes are off, the engine pulls the wagon forwards. A frictional force also acts on the wagon. In what direction does the frictional force act?

1 mark

(ii) The pull of the engine is 5000 N. When the wagon’s speed is increasing, how large is the frictional force? Tick the correct box.

zero

between 0 and 5000 N

5000 N

more than 5000 N

1 mark


(c) After a while, the wagon travels at a steady speed. The engine is still pulling with a force of 5000 N.

How large is the frictional force now?Tick the correct box.

zero

between 0 and 5000 N

5000 N

more than 5000 N

1 mark


When a car is being driven along, two horizontal forces affect its motion.One is air resistance and the other is the forward force.

(a) (i) Explain how molecules in the air cause air resistance.

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

..................................................................................................1 mark

(ii) Explain why air resistance is larger when the car is travelling faster.

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

..................................................................................................1 mark


(b) (i) Compare the sizes of the forward force and the air resistance when the car is speeding up.

The forward force is

..................................................................................................1 mark

(ii) Compare the sizes of the two forces while the car is moving at a steady 30 miles per hour.

The forward force is

..................................................................................................1 mark

(c) The forward force has to be larger when the car is travelling at a steady 60 mph than when it is travelling at a steady 30 mph. Why is this?

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

............................................................................................................1 mark

(d) The forward force is the result of the tyres not being able to spin on the road surface.What is the name of the force that stops the tyres spinning?

.....................................................................1 mark

Maximum 6 marks


QUESTION 6

Anil sits on a mat at the top of a helter-skelter and then slides down a chute around the outside.

chute

A

B

m at

(a) (i) Name two of the forces acting on Anil as he slides from point A to point B.

1. ....................................................................

2. ....................................................................2 marks

(ii) As Anil slides from point A to point B, the forces acting on him are balanced.

Describe Anil's speed when the forces acting on him are balanced.

..................................................................................................1 mark

(b) Anil goes back for a second go. This time he sits on a smooth cushion instead of a mat.

He goes much faster on the cushion. Give the reason for this.

............................................................................................................1 mark


(c) On his third go Anil lies back on the cushion with his arms by his side.

What happens to his speed? Give the reason for your answer.

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

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

............................................................................................................2 marks


In a storm, a small ship was blown onto a beach. Now it is calm and there is no wind. A tugboat is trying to pull the ship off the beach.

(a) The tugboat pulls the ship with a force of 25 000 N.

The ship does not move because of the force of friction acting on it.

(i) Tick one box to show the size of the frictional force acting on the ship.

zero

more than zero but less than 25 000 N

25 000 N

more than 25 000 N

1 mark

(ii) Add an arrow to the drawing to show the direction of the frictional force acting on the ship.

1 mark


(b) When the tide is higher, the tugboat again pulls the ship with a steady force of 25 000 N. The ship begins to move.

Once the ship is off the beach, the tugboat continues to pull the ship with a force of 25 000 N.A frictional force due to the water acts on the ship.

(i) At first, the speed of the ship increases.

Tick one box to describe the frictional force acting on the ship while its speed is increasing.

zero


25 000 N

more than 25 000 N

1 mark

(ii) After a short while, the ship reaches a steady speed. The tugboat continues to pull with a force of 25 000 N.

Tick one box to describe the frictional force acting on the ship while it is going at a steady speed.

zero


25 000 N

more than 25 000 N

1 mark

(iii) The ship is towed to the north. What is the direction of the frictional force acting on the ship?

..................................................................................................1 mark

Maximum 5 marks


QUESTION 8

(a) The ‘two second rule’ is a rule for car drivers. The rule is as follows:

‘Leave enough space between you and the vehicle in front so that you can pull up safely if it suddenly slows down or stops. . . A two second time gap may be sufficient. . . Use stationary objects (eg lamp-posts) to help you keep a two second gap.’

(The Highway Code, 1993)

(i) The traffic is moving at 20 m/s, and a driver is keeping to the ‘two second rule’.What is the distance between the driver and the car in front?

..................................................................................................1 mark

(ii) The traffic increases its speed to 25 m/s, but the driver stays the same distance from the car in front.She sees the car in front pass a lamp post.How long will it take her to reach the same lamp post?

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

................................................................................................s1 mark

(b) The driver decides to check her speedometer while driving along a motorway. She measures how long it takes her to travel 6 km. It takes her exactly 4 minutes.What was her speed in km/h? Show your working.

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

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

....................................................................................................km/h2 marks

Maximum 4 marks


QUESTION 9

Speed cameras are used to detect motorists who break the speed limit. A number of lines 2 m apart are painted on the road. As a speeding car crosses the painted lines, the camera takes two photographs, 0.5 s apart.

(a) (i) How far did the car move between the two photographs? Give the correct unit.

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

..................................................................................................1 mark

(ii) How fast is the car in the photographs moving?

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

........................................................................................... m/s1 mark

(b) It takes 0.0002 s to take each photograph.How far does the car move while the speed camera is taking one photograph?

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

........................................................................................................m1 mark

(c) The speed camera gives out bright flashes to provide enough light for the photographs.How does the light from the flash get back to the camera to produce the photographs?

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

............................................................................................................1 mark

Maximum 4 marks


QUESTION 10

A video recorder is loaded with a tape which plays for 180 minutes.The length of the tape is 260 m.

(a) (i) Calculate the speed of the tape, in metres per minute.

……………………………………….………………………………

……………………………………….………………………m/min1 mark

(ii) What is the speed of the tape in metres per second?

……………………………………….…………………………m/s1 mark

(b) To rewind the tape quickly, a different motor is used, which rewinds the tape at a maximum speed of 1.08 m/s.

(i) At this speed, how long would it take to rewind the tape completely?Give the units.

……………………………………….………………………………

……………………………………….………………………………1 mark

(ii) In fact, it takes slightly longer than this to rewind the tape.Explain why.

……………………………………….………………………………1 mark

Maximum 4 marks


QUESTION 11

A remote-controlled car was timed over a period of 10 seconds. A graph of distance against time is shown below.

20

16

12

8

4

00 2 4 6 8 10

tim e, in seconds

d istance , inm etres

(a) Describe the motion of the car between:

(i) 2 seconds and 6 seconds;

..................................................................................................1 mark

(ii) 9 seconds and 10 seconds.

..................................................................................................1 mark

(b) Calculate the average speed of the car between 0 and 10 seconds. Give the unit.

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

............................................................................................................2 marks


(c) The diagram below shows two of the forces acting on the car when it is moving.

(i) When the motor was switched off, the car slowed down and then stopped.

While the car was slowing down, which of the following was true? Tick the correct box.

Friction was zero and the forward force was greater than zero.

The forward force was zero and friction was greater than zero.

Friction was zero and the forward force was zero.

The forward force and friction were both greater than zero.

1 mark

(ii) Use the graph to find the time when the car started to slow down.

The car started to slow down after ............ s.1 mark

Maximum 6 marks

QUESTION 1

The drawing shows a very old set of scales. It can be used to check the weights of silver coins.


pivo t

pan X pan Y

(a) Rema puts a silver coin in pan X. There is nothing in pan Y.In which direction does pan X move?

…………………………………………1 mark

(b) The table shows the weights of five silver coins.

Silver coin weight in mN

A 106

B 112

C 98

D 112

E 120

Rema puts one coin in each pan of the scales. Which two coins will make the scales balance? Give the letters.

……………… and ………………1 mark

(c) Coin A is placed in pan X, and coin C is placed in pan Y.In which direction does pan X move?

……………………………...1 mark

(d) In another experiment, coin B is placed in pan X, and one of the other coins is placed in pan Y. Pan X goes up.


pan X

pan Y

BR

I

T I S H P EN

CE

BR

I

TI S H P E

N

CE

coin B

co in in pan Y

Which coin is in pan Y? Give the letter.

………….1 mark

(e) Rema knows the weights of the five silver coins in the table. She also has a gold coin.Explain how she could use the coins and the scales to find the approximate weight of the gold coin.

………………………………………………………………………………

………………………………………………………………………………

………………………………………………………………………………

………………………………………………………………………………2 marks

Maximum 6 marks

QUESTION 2

Five people take it in turns to sit on a see-saw. The table gives the weight of each person.

person weight, in N

Jack 510

Ellie 540


Rosie 490

Maggy 540

Andy 560

(a) Andy sits at one end, but there is nobody on the other end.

Andy sits on the see-saw. In which direction does his end of the see-saw move?

...................................................................1 mark

(b) Which two people in the table above could make the see-saw balance?

………………………..……...…......and………………….......………….1 mark

Use information in the table to help you answer parts (c) and (d).

(c) Rosie sits on end A, and Jack sits on end B.


They lift their feet.What happens to each end of the see-saw?Write up or down in the boxes under Rosie and Jack.

1 mark

(d) Ellie sits on end A, and another of the group sits on end B.Ellie's end stays down.

Who could be on end B?

...................................................................1 mark

Maximum 4 marks

QUESTION 3

Tom tries on four types of footwear in a sports shop.

ski boot trainer


ice skate walking boot

(a) (i) When Tom tries on the footwear, which one sinks into the carpet the most?

..................................................................................................1 mark

(ii) When Tom tries on the footwear, what is the same for each type of footwear? Tick the correct box.

the area of the footwear

Tom’s weight on the footwear

the material of the footwear

the weight of the footwear

1 mark

(b) The drawing below shows a snowshoe.

snow shoe

How do snowshoes help people to walk in deep snow?

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

............................................................................................................1 mark


(c) Choose the correct word from the list to complete the sentence below.

air resistance friction gravity magnetism

When Tom is ice skating the force of ................................................

between the skate and the ice is less than when he is walking on a

carpet.1 mark


Ruth is investigating how much a piece of wood can bend. She hangs some masses on the end of the piece of wood and measures how far the wood has bent.

bench clam p p iece of w ood

rule r to m easurehow m uch thep iece of w oodhas bent

m asses

(a) Give the name of the force which pulls the masses downwards.

....................................................................1 mark

(b) The graph below shows Ruth’s results.

1 8

1 6

1 4

1 2

1 0

8

6

4

2

00 1 0 0 2 0 0 3 0 0 4 0 0 5 0 0

d is tan c e th ep ie ce o f w o o d h asb en t in m m

m ass in g


(i) Complete the graph by drawing a straight line of best fit.1 mark

(ii) A mass of 350 g is hung on the piece of wood. How much does the wood bend?

......................….. mm1 mark

Maximum 3 marks

QUESTION 5

The drawing shows a boy with a bow and arrow. He is holding the arrow and pulling it back.

(a) Two horizontal forces act on the arrow. These are the force exerted by the boy’s hand and the force exerted by the string. The arrow is not moving.

The boy pulls the arrow with a force of 150 N. What is the size of the force exerted by the string on the arrow?

...................... N


1 mark

(b) When the boy lets go of the arrow, it starts to move forward.

Explain why it starts to move.

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

............................................................................................................1 mark

(c) The arrow flies across a field and hits a target.

Two forces act on the arrow while it is in the air. Air resistance acts in the opposite direction to the movement, and gravity acts downwards. These two forces cannot balance each other, even when they are the same size. Why is this?

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

............................................................................................................1 mark

(d) The arrow has a sharp pointed end. When the arrow hits the target, the sharp point exerts a very large pressure on the target.

Why does a sharp pointed end exert a larger pressure than a blunt end?

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

............................................................................................................1 mark


A drawing pin is pressed into a notice board.

area 0 .1 m m

area 100 m m

2

2

The pin is pressed into the notice board with a force of 20 N.The head of the drawing pin has an area of 100 mm2.The point of the pin has an area of 0.1 mm2.

(a) What is the size of the force exerted by the point of the pin on the notice board?

........................................................................................................ N


1 mark

(b) Calculate the pressure exerted by the point of the drawing pin. Give the unit.

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

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

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

............................................................................................................2 marks

Maximum 3 marks

QUESTION 7

(a) A ladder is hung on one hook so that it balances horizontally.

Draw an arrow on the diagram below to show the position of the

hook.

1 mark

(b) A window cleaner puts the ladder on his shoulder in the position shown.

(i) The weight of the ladder acts at its centre, as shown. Calculate the turning effect, or moment, about his shoulder due to the weight of the ladder. Give the unit.

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

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


2 marks

The window cleaner hooks his bucket onto the ladder as shown in the diagram.The bucket weighs 15 N and is 0.8 m from his shoulder.

(ii) Calculate the turning effect, or moment, about his shoulder due to the weight of the bucket only.

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

..................................................................................................1 mark

(iii) Calculate the size and direction (clockwise or anticlockwise) of the total turning effect, or moment, about his shoulder due to the weight of the ladder and the weight of the bucket.

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

..................................................................................................1 mark

(c) To keep the ladder and bucket balanced on his shoulder, the window cleaner has to pull down with his hand.

(i) How can he move the ladder on his shoulder to reduce the force his hand has to balance?


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

..................................................................................................1 mark

(ii) How could he change the position of the bucket to reduce the force his hand has to balance?

..................................................................................................1 mark

Maximum 7 marks

QUESTION 8

Karen wants to pump up her car tyre.Her pump has a piston with an area of 7 cm2.

a rea = 7 cm 2

175 N

Karen pushes the handle down with a force of 175 N.

(a) What pressure does she exert on the air in the pump?

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

.................................................................................................N/cm2

1 mark

(b) The air pressure in the tyre is 27 N/cm2.What pressure would be needed in the pump in order to pump more air into the tyre?

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

............................................................................................................1 mark


(c) Another of Karen’s car tyres exerts a pressure of 30 N/cm2 on the road. The area of the tyre in contact with the road is 95 cm2What is the force exerted by the tyre on the road?

.........................................................................................................N1 mark

Maximum 3 marks

QUESTION 9

A pen cap floats in a plastic lemonade bottle three-quarters full of water.If you squeeze the bottle the pen cap sinks to the bottom.If you then let go of the bottle, the pen cap floats to the surface.

p lastic bo ttle

a ir

a ir

w a te r

pen cap

tab le

(a) When the bottle is squeezed what, if anything, happens to:

(i) the distance between the air molecules inside the bottle?

..................................................................................................1 mark

(ii) the distance between the water molecules inside the bottle?

..................................................................................................1 mark

(iii) the pressure of the air trapped inside the pen cap?

..................................................................................................1 mark


(iv) the volume of the air trapped inside the pen cap?

..................................................................................................1 mark

(b) Explain why the pen cap sinks when you squeeze the bottle.

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

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

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

............................................................................................................2 marks


(a)

weight10 N

A vase is held at an angle as shown in the diagram above. When it is released it falls back on its base.

Explain why, in terms of moments.

…..…………………………………………………………………………………

…..…………………………………………………………………………………1 mark


(b)

force

vase tiltsaround th is point

w eight10 N

5 cm

25 cm

In the diagram above, the top of the vase is being given a push. The force is just large enough to make the vase start to tilt.

(i) Calculate the size of the force. Show your working and give the correct unit.

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

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

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

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

..................................................................................................3 marks

(ii) If the base of the vase were wider, a larger force would be needed to make the vase start to tilt. Explain why, in terms of moments.

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

..................................................................................................1 mark

Maximum 5 marks


QUESTION 11

(a) Diagram 1 is a simplified drawing of bones and muscles in a left leg viewed from the outer side.

(i) Muscle A contracts. What effect does this have on the leg?

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

..................................................................................................1 mark

(ii) Muscles are found in antagonistic pairs. Write the letters of the pair of muscles which control the bending and straightening of the leg at the knee.

..................................................................................................1 mark

(iii) When one muscle of an antagonistic pair contracts the other muscle does not relax completely, but maintains some tension.

What is the advantage of maintaining tension in both muscles.

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


..................................................................................................1 mark

(b) Diagram 2 shows the elbow joint. Tissue X covers the ends of the bones at the joint.

(i) Give the name of tissue X. …………………………………………………….1 mark

(ii) Osteoarthritis is a very painful condition. In the joints of people with osteoarthritis small pieces of tissue X break off.Suggest two effects this could have on the joint.

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

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

..................................................................................................2 marks

(c) Tendons are shown in diagram 1 and ligaments are shown in diagram 2. Ligaments can stretch much more than tendons.

(i) Explain why ligaments at the elbow need to stretch.

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

..................................................................................................1 mark

(ii) Explain why it is necessary that tendons hardly stretch at all when a muscle contracts.

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

..................................................................................................1 mark

Maximum 8 marks


9K Summary SheetsSpeeding up

Calculating speed Speed tells us how fast something is going.

We can work out the mean (average) speed of something by using this formula:

mean speed = distance travelled ÷ time taken.

Speed can be measured in: • metres per second (m/s)• kilometres per hour (km/h)• miles per hour (mph).

We can show how things move on a distance–time graph. This graph shows Kieron walking to school.

Forces Smithdon High School 35

Balanced forces are forces which are the same size but work in opposite directions. Unbalanced forces make things change speed, change shape or change direction.

If forces are balanced:• a stationary object stays stationary• a moving object continues to move at the same speed.

If forces are unbalanced:• a stationary object will start to move• a moving object will change its speed or direction.

The motorbike is accelerating because the forward force is greater than the backward force.

The motorbike is going at a steady speed. The forces are balanced.

A car or motorbike uses fuel to move at a steady speed because it needs a force from the engine to balance the forces of air resistance and friction.

The amount of air resistance on something can be reduced by giving it a smooth, streamlined shape. The air resistance increases as the speed increases, so cars use up more fuel per mile when they are travelling fast. Air resistance is caused by air particles hitting the moving object. The particles transfer energy to the object, which is why objects moving through air can get hot.

The forces on a skydiver change during a jump. Her weight is the same all the time, but her air resistance changes during the jump. We can use a speed–time graph to show what happens.


• At A she has just jumped out of the plane so she has only just started to move downwards. Her air resistance is very small.

• At B her air resistance is bigger, but not as big as her weight so she is still gaining speed.

• At C the forces on her are balanced so she falls at a steady speed.

• At D she has opened her parachute. The air resistance force is suddenly a lot bigger than her weight, so she slows down.

• At E the forces are balanced again, and she will continue to fall at a steady speed until she reaches the ground.

9L Summary SheetsPressure and moments

Pressure on solids

A The thumb is putting a force onto the head of the pin. The force is transferred to the point of the pin. This is a very small area, so there is a very large pressure on the board, and the pin goes in.

B The thumb is putting a force on the board. The area of the thumb is much larger than the area of the pin point, so there is only a small pressure on the board. The thumb does not go into the board.

Examples of a small area giving a large pressure:

Sharp knife. Ice skates.

Examples of a large area giving a small pressure:


Snow shoes. Camel on sand.

We can work out the pressure on something by using this formula:

pressure = force ÷ area

Pressure can be measured in: • newtons per square metre (N/m2)• newtons per square centimetre (N/cm2)• pascals (Pa).

1 Pa = 1 N/m2

Pressure in liquids and gasesBoth gases and liquids are fluids. Fluids can flow. Pressure in fluids acts in all directions. The particles in fluids are moving all the time and hitting the walls of containers or other things they come into contact with. The force of the collisions causes pressure which acts in all directions.

The swimmer is floating because pressure in the water provides a force called upthrust, which balances the force of gravity. As you go deeper into the sea, pressure increases because there is more water above you pressing down. Dams are made with thicker walls at the bottom to withstand the pressure.

Uses of pressure in liquids and gases


Gases can be compressed. The pressure in a compressed gas is higher because there are more molecules moving around and hitting the walls of the container. Pneumatic tyres contain compressed air and this keeps the tyre inflated and helps to soften a bumpy ride.

Liquids cannot be compressed. Liquids are used in hydraulic systems which can be used to increase the size of a force. Hydraulics are used in car braking systems.

Example

Pressure = force ÷ area

The pressure on the water is 25 N .5 cm2

This is 5 N/cm2.

The area at the end of the other syringe is 12 cm2.

Force = pressure area

The output force is 5 N/cm2 12 cm2 = 60 N.

LeversForces can be used to turn objects around pivots. A pivot is also known as a fulcrum.

Levers work by magnifying the force that is put in or the distance it moves.

The hammer is acting as a force multiplier.

Moments


A turning force is called a moment. Moments are measured in newton centimetres (N cm) or newton metres (N m).

Small moment. Big moment.

The longer the distance the greater the moment. It is easier to turn the long spanner than the short one.

When an object is balanced, the anticlockwise moment = the clockwise moment.

In the example above:

the anticlockwise moment = 300 N 2 m= 600 Nm

the clockwise moment = 400N 1.5 m= 600 Nm

The clockwise and anticlockwise moments are the same, so the seesaw is balanced or in equilibrium.

Cranes use the principle of moments. The moment from the load is balanced by the moment from the concrete blocks to stop the crane toppling over.

Smithdon High School 40The answers you give to this survey are confidential. You do not have to answer any questions if you do not want to.

Please tick Strongly agree

Agree Disagree Strongly disagree

StandardsI am expecting to do well in this unit

I am on target to do better than I expected

TeachingI have been taught well

I have been given enough help and guidance

Expectations are high in this unit

I have been told regularly how to improve

I am clear about the progress I have made

LearningI feel confident about the end of unit test

I feel prepared for the end of unit test

AttitudesI take pride in my work

I am pleased with my practical work

I have enjoyed this unit

What do you like most about this unit?

What do you think we could improve on / or change?


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