Download File

ACTIVITY 1: FORCES AROUND YOU
We know an unbalanced force is acting if an object changes shape, speed or direction.

Complete the following passage to show your understanding of forces.
A ……force…… is a push, a ……pull……………. or a twist. A force can change the
speed, direction or …………shape………………. of an object.
Forces are classified as ……contact…. forces or …non-contact…………..forces.
Friction is an example of a ……contact……………. force because it is caused when two
surfaces are in contact with each other and trying to slide across each other.
…Non-contact……………... forces include gravity, …magnetic………………….. and
electrostatic forces. We use the term ‘field’ to describe forces that act a distance (i.e. not
caused by contact). We refer to the field that exerts a force on a mass, magnetic
substance or a charged object as gravitational, magnetic and electric fields respectively.

Carry out the following investigation
PART A: CONTACT FORCES
Use the table tennis ball and a straw to answer the following questions.
1. What happens if you blow on the ball when it is moving towards you?
…It slows down and then changes direction (back the other way).
2. What happens if you blow on the ball when it is moving away from you
……It goes faster.
3. What happens if you blow on it when it is moving across in front of you?
…It changes direction away from you.
4. You might want to play a game of ‘blowball’ in a group of four, with two in each team.
Use a straw each and set up two goals and see who scores the most goals.
PART B: NON-CONTACT (FIELD) FORCES
1. Gravitational forces:
Collect a 20 coin and cut out a piece of paper the size of a 20 cent coin.
(a) Drop the paper and 20 cent coin from the same height at the same time. Write
an inference to explain what happened in terms of any forces acting.
Because the paper is lighter (has smaller weight force) it took longer (air
resistance has a greater effect).
(b) Roll the paper into a tight ball repeat the experiment. Write an inference to
explain what happened in terms of any forces acting on the two objects. Be
sure to distinguish between the contact and non-contact forces.
When screwed into a ball it fell at the same time as the coin. This implies that
different weight doesn’t make them fall at different rates, it is just air resistance.
Air resistance is a contact force. Gravity makes them fall and is a non-contact
force.
2. Electrostatic forces:
Tear a piece of paper into small bits and rub a plastic pen on your jumper.
(a) What happens when you bring the pen near the pieces of paper?
The paper sticks to the pen.
(b) How can you tell that the electrostatic force can act a distance?
The paper jumps up and sticks to the pen before the pen reaches the desk.
3. Magnetic forces:
Collect two bar magnets. Feel what happens as you bring the north pole of one
magnet close to the north pole of the other magnet. Repeat the experiment with two
south poles.
Write a generalisation describing the forces that act between two like poles.
They repel each other.
…………………………………………………………………………………………….
PART C: MEASURING FORCES Forces are measured in Newtons (N). This unit is named
after Isaac Newton. Forces are measured using a spring balance.

Collect several different spring balances, e.g. 5 N, 20 N and 50 N. Measure the forces
involved in at least 10 activities, e.g. opening a cupboard door, lifting a shoe, dragging
a chair, sliding a drawer open, lifting a pencil case, pulling a pencil case along your
desk, pulling sticky tape off the bench, opening a can of soft drink, etc. NB. You should
always use the spring balance with the largest range and use smaller ones for greater
accuracy only if the measurement is within its range.

Construct a table to record your measurements in the space below.
Activity
Trial 1 (N)
Lifting tissue box
1.3
Opening a
5.0
drawer
Pencil case
2.9
weight
Pulling down
5.0
periodic table
chart
Opening box
1.0
Lifting guitar
8.0
Empty drink
3.0
bottle
Tongs weight
0.8
Scissors weight
0.7
Lifting iPad
3.7

Trial 2 (N)
1.4
5.0
Trial 3 (N)
1.3
5.0
Average (N)
1.3
5.0
2.8
2.9
2.9
5.0
5.0
5.0
1.0
8.1
4.0
1.0
8.2
3.0
1.0
8.1
3.3
0.9
0.6
3.5
1.0
0.7
3.7
0.9
0.7
3.6
Complete the following questions to show your understanding of forces.
1. (a)
(b)
What is the unit of force and what is its symbol? Newtons (N)
Name three types of forces that can act over a distance rather than by contact.
Gravity, magnetic, electrical
2. You are sitting on a chair.
(a) What are the two balanced forces that are acting on you?
If forces are balanced then an object is not moving (at rest) OR is moving in a straight line at
constant speed.
…Weight force downwards, normal force upwards
(b) What would happen if these forces were not balanced?
…You would sink/fall off chair
3. Imagine you are abseiling down a cliff. What are the two forces acting on you? How
would you know if they are balanced or not?
Gravity pulls you down (Causing a weight force), normal force upwards, air resistance,
friction (of ropes, of shoes with rock)
4. Complete the table below. For the last column, choose from the list below:
starting an object moving/slowing down an object that is moving
balancing another force, and preventing movement
changing the direction of movement
bending an object
SITUATION
OBJECT ON WHICH
FORCE ACTS
WHAT THE FORCE IS
DOING
Changing direction of
movement
ball
parachute
Ugg boot
wheelbarrow
leash
Slowing the cart down
Balancing another force
Starting an object moving
Balancing another force
ACTIVITY 2: SCIENTIFIC EYE (Forces & Friction Videos)

Watch “Push and pull forces” and “Friction” videos on Clickview.
1.
What sorts of forces are there?
..Push, pull, twist
2.
What do all forces do?
..Act on an object and cause a change
3.
Which force pulls you down? gravity.
4.
What is ‘air resistance’?
..The push of air against an object as it moves eg. skydiver
5.
What forces act when someone jumps on a trampoline?
Friction, gravity, air resistance
6.
Give an example of something needing a pull and a lift.
Pull door handle towards you to open door, pedalling on a bike
7.
Why are sea creatures streamlined?
They need to move fast to get away from predators OR to catch prey.
8.
What is friction?
Two objects in contact….friction is the force that acts against the direction of movement.
9.
How can friction be useful?
Stops us falling over, helps tyres grip the road
10. How can it be shown that friction produces heat?
Lighting a fire with flint/steel, rubbing hands together
11. How can friction be reduced?
Using lubricants
12. What practical examples of ‘useful’ friction are shown towards the end of the video?
Walking, running, lighting a fire, jump on a trampoline, hold anything.
ACTIVITY 3: GRAVITY

1.
Watch the Brainpop “Gravity”
Look at the diagram opposite. Choose the
correct word to complete each sentence.
(a)
The force of gravity is a
…………pull………………… (push/pull).
(b)
A gravitational force pulls the spring
…………down………………… (up/down).
(c)
The heavier the object, the
…………greater…………….(less/greater)
the gravitational force.
(d)
The stronger the force, the …more…… (more/less) the spring stretches
(e)
A 10N weight is a …smaller…… (larger/smaller) force than a 20N weight.
(f)
A 20N force stretches the spring …twice…………… (twice/half) as much as a
10N force.
(g)
(h)
Complete the table below.
WEIGHT (N)
STRETCH (cm)
100
8
200
16
300
24
400
32
500
40
Predict how much a 50N weight would stretch the spring based on the table.
……………4cm………………………………………………………………
2.
Imagine you are going on a trip to the planets. Your travel agent has given you this
table showing the force of gravity on each of the planets.
(a)
Where would you weigh the most? ………Jupiter…………………..
What difference would this make to getting around the planet?
……Harder!! ……………
(b)
Where would you be weightless? ………outer space…………
(c)
Suggest why the gravity is similar on Mercury and Mars.
……………Similar size…………………………………
3.
(d)
On which planet would you need the least fuel for blast off? …Pluto……
(e)
How high can you jump on Earth? .......52cm.......................................................
(f)
How high would you be able to jump on the moon? …325cm………….
Identify TWO toys for which gravity plays a role in their operation.
Paddle ball, balance doll, any game with a ball…eg. Soccer, yo-yo
ACTIVITY 4: MAGNETIC FORCES

Carry out an investigation to find out which objects are attracted to a magnet..
1. Identify the objects that were attracted to the magnet. ………………………………...
Chair leg, metal skirting, whiteboard, heater
2. Are all metals attracted to magnets? Give a reason to support your answer.
No! Only iron, nickel and cobalt (and alloys of these) will be attracted to magnets.
3. Of the materials attracted to the magnet, which one was attracted the most?
Metal skirting
4. Which materials seemed able to ‘block’ the magnetic force?
Plastic, some metals, glass, rubber, concrete and wood

Hold different poles of two bar magnets together.
Record whether the magnets attract or repel in each case.
……attract……………………..
……repel……………………..
……repel……………………..
……attract……………………...
Complete the following sentence to summarise your findings.
Like poles ……repel……………….. but unlike poles …attract……………………

Identify any toys that you have ever played with that contained something magnetic.
Magnetics, skateboard, magnetic earrings, magnetic fishing

Record how you might be able to get one magnet to ‘float’ above another in a test tube.
Explain how this behaviour in terms of gravitational and magnetic forces.
Carefully place bar magnetic in test tube. Place another on top with like poles together.
Gravity pulls it down but the repulsive magnetic force pushes it up.
Collect a bar magnet and a horseshoe magnet and a box of paperclips or pins. Hold
one of the magnets above the paperclips or pins and lower it slowly. Lift it up and
observe where the paperclips or pins are attached. Repeat with the other magnet.
1. Which parts of the bar magnet hold the most paperclips?
The poles (each end)
2. Which parts of the bar magnet hold the least number of paperclips?
The middle
3. Write an inference to explain your observations.
The magnetic field is strongest at the poles.
4.
Complete the sentences below.
(a)
A substance which is attracted to a magnet is said to be magnetic
(b)
A magnet can exert a force on a piece of iron without touching it.
(c)
Magnets can be made of iron or cobalt. or nickel
(d)
All magnets have two poles.
(e)
One end of the magnet is called the north pole The other end is called the south
pole
(f)
Two south poles or two north poles are called like poles
(g)
When two magnets push each other apart we say they repel
(h)
Like poles repel and opposite. poles attract.
5.
An electrician has a magnetised screwdriver to help her hold screws. Which of the
following will the screwdriver attract: steel screws, brass screws, aluminium washers,
steel washers, copper wire?
6.
Use the words magnetic and non-magnetic to explain how you can separate a mixture
of small pieces of iron and copper (known as iron filings and copper turnings).
The small pieces of iron are magnetic so you can use a magnet to pick them up and
separate them from the non-magnetic copper.
7.
The magnetic couplings in the Lego train below are either blue or red.
They will link up only if you join a red to a blue. Suggest a reason for this.
The red and blue link up because they are opposite poles and so will attract.
8. Is the bar magnet a permanent or a temporary magnet? Explain your answer.
Permanent. Because they stay magnetic for long periods of time.
ACTIVITY 5: MAGNETIC FIELDS

Carry out the investigation “Mapping the magnetic field”. Please ask your teacher about
the correct technique before you begin to ensure that no iron filings come into contact
with the bar magnet. Record results below.
MAGNETIC FIELD OF BAR MAGNET
1. Where does the magnetic field appear to be the strongest? How do you know this?
The poles because this is where the iron filings were most strongly attracted.
2. What happens to the magnetic field as you get further away from a magnet?
It gets weaker.

Watch the BrainPop on magnetism

Answer the questions below to test your understanding of magnetic fields and forces.
1. What is a magnetic field? Can we see one? Explain your answer.
A magnetic field is a force field that surrounds a magnet. It attracts magnetic
objects. We can’t see it but we can see its effects.
2. The diagram shows a magnet and its magnetic field. A-C are steel ball bearings.
(a) Which ball is most attracted? A
(b) Which ball is least attracted? B
(c) Rank the positions A-C in order of
strongest to weakest magnetic field.
A>C>B
ACTIVITY 6: ELECTRICITY AND MAGNETS

Carry out an investigation to make an electromagnet.
RESULTS:
Voltage of power supply
(V)
9
Number of turns of wire
15
Number of paperclips
picked up
1
9
20
3
1. What effect does increasing the number of turns of wire have?
Increased the magnetism
2. What is the effect of increasing the voltage?
(theoretically) increases the magnetism
3. Explain why an electromagnet is called a ‘temporary magnet’.
It’s only magnetic when electricity is on
4. Describe TWO ways to reverse the poles of your electromagnet.
Reverse the connection on battery; wind wire other way
5.
Arianna made her own electromagnet to find out how the number of windings around a
nail affected the number of paperclips that the nail could pick up. She used the circuit
shown in Investigation 6.10 with the power supply set to 2 volts. Arianna then repeated
her measurements with the power supply set to 4 volts and 6 volts. She recorded her
observations in a table and used it to construct the graph shown below.
(a) How many paperclips did Arianna lift with 20 windings and 6 volt power supply?
11
(b)
Arianna lifted 12 paperclips when the power supply was set to 4 volts. How many
windings were there around the nail at this time?
40
(c)
How many paperclips could Arianna expect to lift with 50 windings around the nail
and the power supply set to 2 volts?
8 (if you extrapolate the graph….ie. take it past the data)
(d)
Suggest a way that Arianna would be able to improve the reliability of her results.
Repeat her experiments several times and take an average.

Watch the BrainPop on electromagnets
Identify THREE differences between electromagnets and regular magnets.
Electromagnets: can be turned on and off, polarity can be reversed, strength can be
controlled.

1.
Complete the following passage to show your understanding of electromagnets.
(a)
When an electric current flows through a wire, the wire has a magnetic field
around it.
(b)
An electromagnet is a temporary magnet made from a coil of wire (insulated
copper wire) wound round a piece of iron. The electromagnet creates a
magnetic field when electricity passes through the coil.
(c)
An electromagnet is similar to a permanent magnet, but it can be turned on
and off by turning the electricity on and off.
2.
Describe THREE uses of electromagnets.
Car wrecking yard, doorbell, sorting scrap metal
3.
4.
Leanne wants to find out whether her electromagnet is as strong as Scott’s. To do
this she counts how many paperclips each electromagnet will pick up. She repeats
her measurement three times for each electromagnet. Her results are as follows:
(a)
Which electromagnet is stronger – Leanne’s or Scott’s? Leanne
(b)
Would the result have been the same if Leanne had tested each
electromagnet only once? Explain.
No because the first test gave identical results but the others didn’t.
The diagram below shows a musical doorbell.
(a)
Explain how the doorbell works.
1. Pressing the switch closes the circuit
2. The electromagnet becomes magnetised
3. The iron is attracted towards the electromagnet
4. The donger hits the chimes
(b)
When the switch is pressed and then released, would the bell go ‘ding-dong’ or
‘dong-ding’? Give a reason for your answer.
Dong-ding because it dongs before it dings (duh)
ACTIVITY 7:
ATOMS & ELECTRICAL CHARGE
Matter (anything with mass) is composed of tiny particles called atoms. Atoms are far too
small to be viewed with the naked eye, but there is a lot of scientific evidence which suggests
they exist. Atoms are themselves composed of small particles that are known as subatomic
particles. The three basic types of subatomic particle are protons, electrons and neutrons.
The protons and neutrons are located in the central core of the atom, called the nucleus and
the electrons orbit the nucleus as shown above. The protons have a positive charge, the
electrons have a negative charge and the neutrons have no charge.
The materials we see and touch in our everyday lives do not carry an overall charge. It is
safe to pick objects up without fear of being ‘zapped’. This is because the atoms which make
up the objects carry no overall charge because they have the same number of positive
charges (protons) and negative charges (electrons). We say they are electrically neutral.
In a previous activity, you rubbed a plastic pen and it attracted pieces of paper because it
was charged. Similarly, you can rub a balloon or plastic ruler on wool to attract water or hair.

Carry out a static electricity investigation
1. Describe the movement of the single balloon. Doesn’t do much
2. Does the rubbed balloon have the same charge as the woollen cloth? Explain.
No. Electrons have moved from the wool to the balloon so the wool is positively
charged and the balloon is negatively charged.
3. Describe the movement of the two balloons. repel
4. Do the rubbed balloons have like or unlike charges? Explain.
Like
5. Complete the sentence: Object with like charges repel each other and objects with
unlike charges attract each other.

Watch the BrainPop on static electricity
Whilst it is difficult to change the number of protons in atoms (because they are contained in
the nucleus of the atom), it is relatively easy to change the number of electrons in some
objects. This is exactly what we are doing when we rub rods or other plastic materials with
material such as wool or silk. Two specific examples are described below”
e.g. When a perspex rod is rubbed with silk, the rubbing removes some electrons from some
of the atoms making up the perspex. These electrons are transferred to the silk cloth.
1.
What charge will a perspex rod carry after it has been rubbed by silk? positive
2.
What about the charge on a silk cloth? negative
When an ebonite rod is rubbed with wool, the opposite happens. This time, electrons are
removed from atoms in the woollen cloth and are transferred to the ebonite rod.
3.
What charge will the ebonite rod carry after it has been rubbed by the wool?negative
4.
What about the woollen cloth? positive
These two situations (i.e. ‘charging’ an object) are described in the diagrams below:
The only way
to charge an
object is to
add or remove
electrons!
silk cloth

Carry out The Van de Graaff generator” investigation
PART A
Once the Van de Graaff generator has become charged, placing the rod near
the dome causes a spark which causes the dome to become earthed (lose its charge).
PART B
1. What happens to the wool? Initially it is attracted but then it picks up electrons and is
repelled.
2. Explain why this happens in terms of the charges on the dome and on the wool.
Opposite charges attract and like charges repel.
ACTIVITY 8: MORE ON STATIC ELECTRICITY

Carry out a “defying gravity” investigation
1. Explain the behaviour of the water and balloon in your own words.
The water bent towards the rod.
2. Explain the effect of the cloth on the balloon.
It made the balloon pop (from friction heat)
3. The two particles of an atom that carry electric charge are the proton (with a positive
charge) and the electron (with a negative charge).
4. A plastic ruler becomes negatively charged when it is rubbed with a woollen cloth.
(a) Describe what has happened to the cloth and ruler at a subatomic level.
Electrons move to the ruler from the cloth, so the ruler becomes negatively
charged and the cloth becomes positively charged.
(b) As the ruler becomes negatively charged, the cloth becomes positively charged
because it now has fewer electrons than before
5. Two positively charged objects would be expected to repel each other.
Two negatively charged objects would be expected to repel each other.
Oppositely charged objects would be expected to attract each other.
6. Explain using a diagram how a neutral object gets attracted to a charged object.
7. What is term used to describe the release of built up charge? Earthing
8. Two balloons are hanging on threads next to each other, but not touching. They
begin to move away from each other. If one of the balloons is positively charged,
identify the charge of the other balloon.
Positive
9. Explain why the student touching the dome of a Van de Graaff generator would be
wearing rubber soled shoes and standing on a plastic mat.
To insulate the student and stop the electrons flowing to the ground.
10. Use the following list of observations to determine whether balloons A, B, C and D
are positively or negatively charged. Balloon E is known to be positively charged.
 Balloon A is attracted to balloon B.
 Balloon D is attracted to balloon E.
 Balloon C repels balloon A.
 Balloon B repels balloon D.
A positive
B negative
C positive
D negative
11. If a pen is rubbed with a woollen cloth, it can attract a small piece of paper.
(a) Is the pen neutral or charged? positive
(b) Is the small piece of paper neutral or charged? neutral

Complete the following table to compare electrostatic forces and magnetic forces.
electrostatic forces
magnetic forces
Both are non-contact forces
similarities
For both, opposites attract and like poles/charges repel
differences
Positive and negative
North and South
Created by electron movement
Created around iron, nickel,
cobalt
Are always temporary
Are permanent or temporary