Science Interactive LTD Copyright 2005
Science Interactive LTD
Science base multimedia CD-ROM for PC is a collection of 38 units or tools totalling over 1150
PowerPoint slides. Each unit covers a wide range of different delivery and learning styles, offering an
exciting way to involve your pupils during lessons or revision sessions. All styles of teaching and
learning are supported through use of high quality images, graphics, challenging exercises and
questions. Units can be used in the classroom via an interactive whiteboard, data projector or used
during individual study via a PC or school network.
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Unit 1: The Digestive System Unit 20: Crude Oil and its Products
Unit 2: The Circulatory System Unit 21: Rock Cycle
Unit 3: Healthy Body and Immunity Unit 22: Elements, Molecules and Compounds
Unit 4: The Respiratory System Unit 23: Ionic and Covalent Compounds
Unit 5: Nervous System and the Senses Unit 24: The Halogens, their Uses and Compounds
Unit 6: Human Homeostasis Unit 25: The Noble Gases, their Properties and Uses
Unit 7: Hormones and the Endocrine System Unit 26: Rates of Reaction
Unit 8: Drugs and Bad Body Maintenance Unit 27: Energy
Unit 9: Photosynthesis in Green Plants Unit 28: Generating Electricity and its Domestic Use
Unit 10: Water Transport in Plants Unit 29: Electricity
Unit 11: Flow of Energy and Elements through the Environment Unit 30: Light and the Electromagnetic Spectrum
Unit 12: Mitosis and Meiosis Unit 31: Radioactivity
Unit 13: Inheritance and Selection Unit 32: Newton's Forces and the Effects of Forces
Unit 14: Evolution and Human Impact Unit 33: Earth and Space
Unit 15: Genetic Engineering Unit 34: The Earth and Plate Tectonics
Unit 16: The Periodic Table and its Elements Unit 35: The Alkaline Earth Metals
Unit 17: The Alkali Metals Unit 36: Sound and Hearing
Unit 18: Metals and their Properties Unit 37: Natural Forces
Unit 19: The Transitional Metals Unit 38: Cells, Tissue, Organs and Organs systems

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Unit 32
Newton’s Forces and the Effects of Forces

Unit 32: Newton’s Forces and the Effects of Forces Science Interactive LTD Copyright 2005
Understand: Keywords:
That there are three types of natural forces, Forces, Newtons, Magnetism, Balanced,
1.
magnetism, electrostatic and gravity. Unbalanced, Gravity, Electrostatic, Speed,
That the size of a force is measured in Velocity, Terminal, Acceleration,
2.
Newtons. Deceleration, Air resistance, Stopping,
Some examples of balanced forces in action. Kinetic, Work done, Joules & Energy.
3.
That a unbalanced force can make an object
4.
accelerate, decelerate, change direction or
change shape.
How to calculate speed, velocity and
5.
acceleration of a moving object.
How to interpret distance, speed and velocity
6.
time graphs.
The stopping distance for cars at different
7.
speeds and how factors like weather and road
conditions affect overall stopping distances.
What is air resistance and the factors that
8.
determine its value.
Newton’s first law of motion.
9.
Newton’s second law of motion.
10.
Newton’s third law of motion.
11.
How to calculate the kinetic energy of a moving
12.
object and work done by a force. Click mouse to begin
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Natural forces
There are three types of naturally occurring forces. These forces cannot be seen, but we
can observe the effects of these forces, for example an a_______ falling towards Earth. In
1666, Newton was the first person to answer why objects fall to Earth. We can also see the
effects of magnetic and electrostatic forces in action. Compared to g________, magnetic
and electrostatic forces are relatively strong. Gravity is the smallest in magnitude of all the
three forces. How could you design an experiment to show that magnetic and electrostatic
forces are stronger than gravity ?
Three types of forces: Word bank: apple gravity
Gravity Magnetism Electrostatic
Diagram
Gravity is the force of attraction Magnetism is the attraction An electrostatic force is the
Notes
between objects with mass. between bar magnets or attraction or repulsion between
Gravity is measured in Newtons. magnetic metals. There are only charged objects. Oppositely
On Earth the gravitational force three metals which are charged objects attract one another
is approximately 10 Newtons per magnetic: Iron nickel and whereas, objects with the same
kilogram (10 Nkg-1) cobalt. charges repel one another.

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Balanced forces one
Although you cannot see forces, we can see the effects of forces and the resulting actions. If an
unbalanced force acts on a object, it will either s_______ up, slow down, change direction or be
squashed. When forces are balanced an object in motion will tend to stay in motion, and an
object at rest will tend to stay at rest unless the object is acted upon by an outside force. When
you are sitting on a chair, gravity exerts a f______ pulling your mass down, with the chair
exerting an equal and opposite force on your body. Unless there is an external force acting on
you, the chair and you will stay at rest. Give three other examples of objects that are at rest ?
Balanced forces: Word bank: speed force
Sitting down Lifting weights London bus
60,000 N
100 N
Diagram 550 N
Gravity
Gravity
Gravity
Up thrust
Up thrust
Muscle
60,000 N
100 N
550 N
Notes Gravity pulls downwards on Gravity pulls downward on the Gravity pulls downward on the
the female with a force of 10 kg weight with a force of red bus with a force of 60,000 N.
550 N. The chair is pushing 100 N. The arm muscles are The ground is pushing upwards
upwards with the same force pushing upwards on the weights with the same force of 60,000 N,
of 550 N. with the same force of 100 N. preventing the bus from sinking.

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Balanced forces two
Understanding balanced forces is simple. We can use arrows to represent the size and direction
of a force. The arrow shows the direction of the force with the size of the force being given in
newtons (N) An object will stay at rest or not start to move, if the forces acting on it are
balanced. What is more difficult to understand, is that an object will continue in m_______ at a
s_______ speed when the forces are balanced. A cyclist will achieve a steady speed, where the
force applied by the muscles through the gears and wheels is equal to the force of internal
resistance and air resistance. Why is it easier to ride behind of a group of cyclists...Explain ?
Balanced forces: Word bank: motion steady
Harrier Jump Jet Boat sailing Building
3,000,000 N
60,000 N
Diagram 30,000 N
Gravity
Gravity
Gravity
Up thrust
Up thrust
Up thrust
3,000,000 N
60,000 N
30,000 N
Gravity pulls downward on Gravity pulls downward on the Gravity pulls downward on the
Notes
the jet with a force of boat with a force of 60,000 N. building with a force of
30,000 N. The thrust of the The up thrust from the water is 3,000,000 N. The ground or
jet engines is pushing pushing upwards on the boat building foundations are pushing
upwards on the jet with the with the same force of upwards with the same force of
same force of 30,000 N. 60,000 N. 3,000,000 N.

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Unbalanced forces one
Although you cannot see forces, we can see the effects of forces and the resulting actions. If an
unbalanced force acts on a object, it will either speed up, slow down, change direction or be
squashed. On a roller coaster, g________ and the forces it exerts on your body will accelerate
you from the start giving you the sensation of falling. Rapid a____________, twisting and
turning gives you that sensation of a near vertical drop whilst still being safe. The force of
gravity is far bigger than the force of friction between the moving parts. Why would a roller
coaster on the moon’s surface be less scary ?
Unbalanced forces: Word bank: gravity acceleration
Roller Coaster Sprinters Free Falling
Diagram 750 N
5,000 N
Gravity
Gravity
400 N 50 N
Pull
Push
Air resistance
Friction
250 N
750 N
In this example, two forces In this example, two forces exists; In this example, two forces exists;
Notes
exists; Gravity and friction. The work done by the muscles and Gravity and air friction. The
largest force is gravity pulling internal friction. The largest force largest force is gravity pulling the
the mass of the roller coaster is produced by muscles propelling mass of the parachutist
and people downwards at forward the sprinter along the downwards at an acceleration rate
track at a speed of around 10 ms-1.
10 m/s2. (ignoring air resistance) of 10 m/s2 (ignoring air resistance)

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Unbalanced forces two
An unbalanced force provided by a car or lorry’s combustion engine can accelerate the moving
vehicle in a forward direction. Engines provide the force to move vehicles like a car forward.
This force is sufficient to overcome the internal r___________ of all the moving parts, the
friction between the tyres and the road surface and air resistance as the car moves forward.
Continue to put you foot on the accelerator pedal and the car reaches a maximum top speed.
This is where the force of the e________ is equal to the drag created by the combined internal
resistance and air resistance. Why are cars designed with a streamlined shape ?
Unbalanced forces: Word bank: resistance engine
Crashes Burn out Space shuttle launch
Diagram 1,000,000 N
Gravity
Thrust
Push Pull
Push Wall strength
2,000,000 N
12,500 N
25,000 N 2,500 N
10,000 N
In this example, two forces In this example two forces exist. In this example two forces exist.
Notes
exists. The forward push of the The forward push of the engine The upward thrust provided by the
car and the wall’s strength. The and the friction between the tyres shuttle engines and the downward
largest force is the forward push and tarmac. The largest force is pull of gravity on the shuttles
of the car which is far higher the forward push of the engine mass. The largest force is the
than the overall strength of the which drives the wheels during upward thrust of the shuttle
wall. this burnout. engines.

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Working with resultant forces
Both the size and the direction of a force is important. A force is called a vector quantity. We can
show the direction of the force by using an arrow drawn in a particular direction. The size of the
force acting in any given d__________ can be indicated using a scale – for example, one centimetre
for one Newton or by writing above the arrow, the size of the force in Newtons. Forces are always in
pairs, so the resultant or overall force must be calculated. Work through these examples, giving your
answers in Newtons ?
Resultant forces: Word bank: direction
Problem one Problem two Problem three
750 N 10 N
8000 N
Gravity
Gravity
Gravity
20 N 2N
Friction
Forward
1kg
Forward push Air resistance
Air resistance
450 N
20000 N
Up thrust
Up thrust
200 N 10 N
8000 N
A gravitational force of 750 N is There are four forces acting on a car: (i) There are four forces acting on the
acting on the free falling man. Air Downward force of 8000 N, (ii) Upward one kilogram block: (i) Downward
resistance acts in the opposite force of 8000 N, (iii) Forward engine force of 10 N, (ii) Upward force of
direction with a value of 200 N. The force of 20,000 N (iv) Air resistance 10 N, (iii) Forward push of 20 N (iv)
resultant force acting downwards force of 450 N. Work out the total Friction force of 2 N. Work out the
and accelerating the parachutist is resultant force. Which way would the total resultant force. Which way
750 N -200 N = 550 N. car move ? would the block move ?

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Forces and the effects of forces
Forces cannot be directly observed, but the effects of a force can. A force measured in newtons
exerted on an object can result in many different resultant actions. Forces affect the way objects
move. You cannot see a force that changes an objects s________ or direction. A car accelerates
forwards due the force exerted by the car’s engine on the front wheels. If you continue to
accelerate, the car will achieve its maximum top speed, where the force of the e_________ is
equal to the force of internal resistance and air resistance. If you apply a breaking force the car
will slow to a stop Why do fast cars have the best brakes fitted ?
Forces and the effects of forces: Word bank: speed engine
Speed Velocity Acceleration Deceleration
Diagram
ms-1 ms-1 (0 to 3600) m/s2 -m/s2
Units
Speed describes the distance Acceleration describes the change of Deceleration is the
Notes
travelled by an object and the time velocity and the time taken for that change in velocity
taken. Velocity describes the change to occur. Constant acceleration when objects slow
distance travelled and the time taken, gives a straight line, whereas changing down. It always
but it also describes the direction of acceleration gives a curved line on a has a negative
travel. velocity time graphs. value.

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Speed one
The speed of a moving object describes the distance travelled in metres over time in seconds.
Knowing the speed of an object, allows you to calculate how long it will take the moving object
to cover a certain d_________. Calculating the speed in metres per second (ms-1) of an object is
simple using the following formula:
Distance travelled (m)
Units for speed = ms-1
Speed =
Time taken (s)
Calculating speed: Word bank: distance
Lorry Sports car Cyclist Sprinter
Diagram
Distance (m) 2000 m 2000 m 2000 m 2000 m
Time taken (s) 150 s 60 s 200 s 400 s
Speed (ms-1) _____________ ? _____________ ? _____________ ? _____________ ?
Notes Using the equation above, work out the speed of the lorry, sports car, cyclist and sprinter.
Also calculate how long in time, it would take each object to cover 10 km (10,000 m)

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Speed two
Distance time graphs show distance travelled over time. The graph below shows a bus journey:
The bus left the depot and took 200 seconds to travel 150 metres to a set of traffic lights. The
bus waited here for 200 seconds while the lights changed to green. The bus then took a further
50 seconds to travel 100 metres. It then took 200 seconds to travel 50 metres and then a further
100 seconds to travel a further 100 metres. It then stopped back at the bus station. The total
time for the journey was 750 seconds with the total distance covered being 400 metres.
Distance time graphs:
Displaying the bus journey using distance time graphs
F
Diagram
400 E
Distance travelled (m)
350
D
300
250
C
200 B
150
A
100
50
0
0 100 200 300 400 500 600 700 800
Time taken (s)
Table Distance travelled (m) 0 150 150 250 300 400 400
Time taken (s) 0 200 400 450 650 750 800
Calculate the following from the information given above: (a) Work out the average speed for the
Notes
entire bus journey. (b) At what point was the bus travelling the fastest speed (c) At what point was
the bus travelling at its slowest speed. (d) For how many seconds in total was the bus at rest.

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Speed three
Using distance time graphs, you can see that the steeper the slope, the greater the object’s
speed. We can use the gradient of the slope to calculate the speed of the moving object:
Change in y (distance)
Units for speed = ms-1
Speed = Gradient of distance time graph Gradient =
Change in x (time)
Using the graph, the speed at point C is worked out by dividing the distance travelled
(250 m..change in y) by the time taken (250 s..change in x) This gives a speed or gradient of 1 ms-1.
Speed and gradients:
Distance time graph Distance time graphs
A B
D
distance (m)
distance (m)
400
Distance travelled (m)
350
C
300
250m
250
time (s)
200 B time (s)
150 C D
A 250s
100
distance (m)
distance (m)
50
0
0 100 200 300 400 500 600 700 800
Time taken (s)
time (s)
time (s)
Calculate the following from the information given above: (a) Work out speed or gradient of the
moving object at points A and B. (b) Work out the total distance travelled. (c) Work out the
average speed of the moving object over the 700 seconds. (d) Which graphs (A, B, C or D) shows
an object with (i) the lowest speed (ii) the highest speed (iii) zero speed.

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Using distance time graphs
Using distance time graphs is simple. The information provided by the graph tells us the speed
or velocity of the moving object and the total d__________ travelled over time. You can see
that the steeper the slope, the greater the object’s speed. We can use the g__________ of the
slope to calculate the speed of the object. Also the total distance travelled by the moving object
can be determined by using the graph.
Using distance time graphs: Word bank: distance gradient
Distance time graph Questions
Question Answer
B A
400
Which objects are not moving at all at
the end ?
300
Which object is moving at the fastest
Distance travelled (m)
speed at the end ?
C Which object took 800 seconds to travel
200
400 metres. Calculate its average speed.
100 Which object stops moving after 300
D seconds ?
0 Which object travels the least distance.
0 100 200 300 400 500 600 700 800
Calculate its average speed ?
Time taken (s)
Remember the following equation:
Change in y (distance)
Units for speed = ms-1
Speed = Gradient of distance time graph Gradient =
Change in x (time)

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Velocity
The speed of an object tells us how fast its travelling (distance travelled over time taken),
whereas using velocity tells us the speed of an object and the d___________ it is travelling.
The direction of an object can be given quite simply as towards or away from us, or as a
bearing having a value from 0 to 360 degrees.
Distance travelled (m)
Units for velocity = ms-1 (0 to 360o)
+ Direction (0 to 360o)
Velocity =
Time taken (s)
Velocity: Word bank: direction
Motorway traffic Coming towards you Going away from you
Diagram
Motorway traffic is a good
Notes A sports car that is coming A sports car that is going away
example of how velocity gives toward you at very high from you at very high velocity
us more information than velocity may cause you to would cause you no anxiety at
speed. In the fast lane, in both
move out of its path. How all. How would you say away
directions the speed is the same
would you say towards you from you using degrees (0 to
at 70 mph, but the direction is
using degrees (0 to 3600) ? 3600) ?
opposite being north or south.

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Changing velocity one
Moving objects change their velocity (accelerate or decelerate) when they move from rest to a
steady velocity and then back to rest again. Using a v_________ time graph, we can show how
the velocity of a moving object changes with time. Care must be taken, because velocity time
graphs are much more complicated, when compared to distance time graphs. The velocity time
graph below shows a car accelerating from 0 ms-1 to 35 ms-1 over 20 seconds to join the
motorway and then maintaining a ‘steady speed’ of 35 ms-1 for a further 60 seconds.
Changing velocity: Word bank: velocity
velocity time graph...car Acceleration
0 to 60 mph in 3.5 secs
0 to 60 mph in 22 secs
40
Steady velocity
30
ing
Velocity (ms-1)
ra t
20
ele
0 to 20 mph in 2 secs 0 to 60 mph in 2.9 secs
c
part b
part a
Ac
10
0
0 10 20 30 40 50 60 70 80
Time taken (s)
The graph can be separated into two parts: Part A The car is speeding up from rest (0 ms-1) to a final
velocity of 35 ms-1 over a period of 20 seconds. It has a constant acceleration giving the graph a straight
line appearance. The steeper the slope the greater the acceleration. Part B When the car has joined the
fast lane, it travels at a constant speed of 35 ms-1 for a further 60 seconds. At a constant velocity, the
graph is a horizontal straight line. From the graph, find the car’s velocity after 5 and 10 seconds.

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Changing velocity two
Just like a distance time graph, we can use a velocity time graph to find out how far in metres an
object travels. Working out the a_______ under the graph will give us the total distance travelled. In
the example below, it is easier to break the graph into two parts, a triangle and a rectangle. Work out
the area of both and then add one to the other to find out the total d__________ travelled. Work out
the total distance travelled using the following formulae:
Area of rectangle = base x height
Area of a triangle = ½ base x height
Changing velocity: Word bank: area distance
Distance time graph...car Working out total distance travelled
40
Steady velocity
½ x base x height
30
ing
Velocity (ms-1)
ra t
20
ele
c
part b
part a
Ac
10
base x height
0
0 10 20 30 40 50 60 70 80
Time taken (s)
Working out the area of both parts gives us the total distance travelled by the car:
Area of a triangle = ½ base x height ½ x 20 x 35 = 350 m 350 m
Part A:
Area of rectangle = base x height 60 x 35 = 2100 m 2100 m
Part B:
(Distance travelled) Total _______________ ?

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Acceleration one
Acceleration of a object is the change in velocity over a certain time period. Calculating
acceleration requires the following information: Starting velocity (v), final velocity (u) and the
t______ taken for that change to occur (t) Calculating the acceleration of an object is simple
using the following formula:
Final velocity (v) – Staring velocity (u) v –u
Units for acceleration = m/s2
Acceleration =
Time taken for change t
Acceleration: Word bank: time
Sports car Sprinters Free falling Cyclist
Diagram
20 ms-1 0 ms-1 0 ms-1 5 ms-1
Starting velocity
60 ms-1 10 ms-1 40 ms-1 15 ms-1
Final velocity
Time taken 2 seconds 0.5 seconds 4 seconds 2 seconds
Acceleration 60-20/2 = 20 m/s2 _______________ ? _______________ ? _______________ ?
Notes Work out the acceleration of each moving object by dividing the change in velocity by
the time taken for that change to occur. Units for acceleration should be m/s2.

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Acceleration two
Velocity time graphs show the changes in velocity over time. The graph shows a cyclist’s
journey: The cyclist left his house and took 10 seconds to change his velocity from 0 ms-1 to
7.5 ms-1. He then travelled at a c________ velocity of 7.5 ms-1 for a further 30 seconds. He then
accelerated from 7.5 ms-1 to 15 ms-1 taking 5 seconds. He then travelled at a constant velocity
of 15 ms-1 for 10 seconds. He then decelerated from 15 ms-1 to complete rest (0 ms-1) over 10
seconds. He then remained at rest for 10 seconds. He then accelerated from rest to 5 ms-1 taking
just 5 seconds, where he continued at a constant speed of 5 ms-1 for 10 seconds.
Changes in velocity and acceleration: Word bank: constant
Velocity time graph....cyclist Velocity time graphs
A B
velocity (ms-1)
velocity (ms-1)
20
D
15
C
Velocity (ms-1)
time (s)
B
10 time (s)
E
C D
H
A
velocity (ms-1)
velocity (ms-1)
5
G
F
0
0 10 20 30 40 50 60 70 80
Time taken (s) time (s)
time (s)
Calculate the following from the information given above: (a) Work out the total distance travelled by the
moving cyclist (From working out the total area beneath the line graph you can work out the total distance
travelled (b) Which graphs (A,B,C or D) shows an object with (i) the lowest constant acceleration (ii) the highest
constant acceleration (iii) Constant velocity, zero acceleration (iv) Constant deceleration.

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Acceleration three
Using velocity time graphs, you can see that the steeper the slope, the greater the object’s acceleration or
deceleration. We can use the gradient of the s_______ to calculate the object’s change in velocity:
Change in y (velocities)
Acceleration = Gradient of the velocity time graph Units for acceleration = m/s2
Gradient =
Change in x (time)
Using the graph, the acceleration of the object at point C is worked out by dividing the change in velocity
(30 ms-1 – 20 ms-1= 10 ms-1...change in y) by the time taken for that change to occur (15 s...change in x)
This gives a acceleration or gradient of 0.67 m/s2.
Changes in velocity and gradients: Word bank: slope
Velocity time graph...car Working out acceleration
0 ms-1
Starting velocity
150 ms-1
40 Final velocity
D Time taken 60 s
30
C
Velocity (ms -1)
Acceleration ________ ?
10ms -1
20
B E
0 ms-1
Starting velocity
15s
A
10
20 ms-1
Final velocity
5
F
0
Time taken 4s
0 10 20 30 40 50 60 70 80
Time taken (s) Acceleration ________ ?
Calculate the following from the information given above: (a) Work out the total distance travelled by
the moving car (from working out the total area beneath the line graph you can work out the total distance
travelled (b) Work out the acceleration values for the plane and the ice skater using the formula...Change in
velocity/time taken for that change to occur...units m/s2.

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Using velocity time graphs
Using velocity time graphs is simple. The information provided by the graphs tells us the
acceleration or change of velocity of the m_________ object and the total distanced travelled
over time. You can see that the s________ the slope, the greater the object’s change in velocity.
We can use the gradient of the slope to calculate the acceleration of the moving object. Also,
the total area under the graph tells us the total distance travelled over time.
Using velocity time graphs: Word bank: moving steeper
Velocity time graph Questions
Question Answer
B
40
Which objects has the highest
E constant acceleration ?
D
A
30
Which object has zero acceleration
and a constant velocity of 20 m-1 ?
C Which
20
object has changing
Velocity (ms-1)
acceleration over 800 seconds.
10
Which object accelerates to 30 ms-1,
decelerates and then is at rest ?
0
Which object travels the greatest
0 100 200 300 400 500 600 700 800
Time taken (s) distance ?
Remember the following equations:
Change in y (velocities)
Acceleration = Gradient of the velocity time graph Units for acceleration = m/s2
Gradient =
Change in x (time)

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Acceleration and gravity one
A free falling object not subject to air resistance will accelerate to Earth at 9.81 m/s2. You
may have heard of Galileo’s experiment, where he dropped a heavy and light ball with the
same shape from the leaning tower of Pisa at the same time. He observed them falling,
accelerating at the same r______ and hitting the ground at exactly same time. This is
because all objects regardless of their mass accelerate at the same rate (assuming no air
resistance.) In a vacuum, which would land first a feather or a coin ?
Galileo’s experiment and the leaning tower of Pisa: Word bank: rate
Leaning tower of Pisa Notes Calculation
Galileo’s experiment: The two balls Time (s) Velocity
with very different masses are
1 10 ms-1
released at the same time. They also
hit the ground at the same time, 2
proving that all objects accelerate at a
constant speed due to gravity and 3
regardless of their mass.
4
Calculation: Calculating acceleration,
we can use a value of 10 m/s2. Work 5
out the velocity of the accelerating
object after 1,2,3,4,5 & 6 seconds 6
assuming there is no air resistance.
10
What is the object’s final velocity ?

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Acceleration and gravity two
If you take a ride on any rollercoaster, at any theme park, designers exploit gravity and other
forces to give you the ‘ride of your life.’ Gravity and the forces it exerts on your body will
a__________ you from the start, giving you a sensation of falling. Rapid acceleration, twisting
and turning gives you that sensation of a near vertical drop whilst still being safe. The force of
gravity on a vertical drop rollercoaster pulls the m______ of the car and you downwards,
accelerating you at nearly 10 m/s2. Why would a rollercoaster on the surface of Jupiter be much
more exciting. If the value of g on Jupiter is 26 N/kg, what would your acceleration rate be ?
Gravity and the rollercoaster: Word bank: accelerate mass
Roller coaster Questions
A 1: At which point does the ball
have maximum kinetic energy and
minimum gravitational potential
energy ?
2: At which point does the ball
B
have maximum gravitational
potential energy and zero kinetic
energy ?
D
3: At which point does the ball
E
C have zero kinetic energy ?
4: At which point does the ball
have decreasing kinetic energy and
increasing gravitational energy ?

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Acceleration and gravity three
Gravity on Earth causes all objects with a mass to fall and accelerate towards Earth’s surface.
In practise, Earth’s atmosphere subjects all moving objects to air r___________. This is the
upward push of atmospheric air molecules exerted on a falling object. It requires a large
amount of energy to push the air molecules out of the way during free fall. Because of this
special type of friction, a f___________ object will reach a final or terminal velocity of about
50 ms-1. Terminal velocity is where the forces of gravity pulling you downwards is equal and
opposite, to the upward force of air resistance. This velocity is sufficient to kill you, should you
fall from a high building or your parachute fail to open.
Terminal velocity: Word bank: resistance falling
Free fall Re-entry Asteroids
Diagram
Gravity
Gravity
Gravity
Air resistance
Air resistance
Air resistance
Free falling, without a Spacecraft can travel an amazing Asteroids, large lumps of space
Notes
parachute, gravity accelerates 30,000 km per hour on re-entry debris can travel at over 100,000 km
you to Earth’s surface reaching causing the tip of the craft to per hour, largely burning up because
a terminal velocity of 50 ms-1. warm to 1600oC. Without heat of heat caused by air resistance.
proofing the re-entry vessel Most asteroids and meteors never
Nothing beats the sensation of
would fail. reach the Earth’s surface.
free falling !

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Deceleration one
Velocity time graphs show the changes in velocity (acceleration and deceleration) travelled
over time. The graph below shows a cyclist’s journey: The cyclist left his house and changed
his velocity from 0 ms-1 to 7.5 ms-1 over 10 seconds. He then travelled at a constant velocity of
7.5ms-1 for a further 10 seconds. He then decelerated from 7.5 ms-1 to 2.5 ms-1 taking 5
seconds. He then travelled at a constant velocity of 2.5 ms-1 for 10 seconds. He then accelerated
from 2.5 ms-1 to 15 ms-1 taking 10 seconds. He then remained at a constant velocity of 15 ms-1
for 10 seconds. He then decelerated from 15 ms-1 to rest (0 ms-1) taking a further 25 seconds.
Changes in velocity and acceleration:
Velocity time graph....cyclist Velocity time graphs
A B
velocity (ms-1)
velocity (ms-1)
20
F
15
Velocity (ms-1)
E time (s)
10 time (s)
B G
C D
C
A
velocity (ms-1)
velocity (ms-1)
5
D
0
0 10 20 30 40 50 60 70 80
Time taken (s) time (s)
time (s)
Calculate the following from the information given above: (a) Work out the total distance travelled by the
moving cyclist (From working out the total area beneath the line graph you can work out the total distance
travelled (b) Which graphs (A,B,C or D) shows an object with (i) the lowest constant deceleration (ii) the
highest constant deceleration (iii) Constant velocity, zero acceleration (iv) Constant acceleration.

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Deceleration two
Using velocity time graphs, you can see that the steeper the slope, the greater the object’s acceleration or
deceleration. We can use the gradient of the slope to calculate the change in velocity of the object:
Change in y (velocities)
Deceleration = Gradient of the velocity time graph Gradient = Units for deceleration = -m/s2
Change in x (time)
Using the graph, the deceleration of the object at point C is worked out by dividing the change in velocity
(30 ms-1 – 15 ms-1= -15 ms-1...change in y) by the time taken for that change to occur (20 s...change in x)
This gives a deceleration or gradient of -0.75 m/s2.
Changes in velocity and gradients:
Velocity time graph...car Working out deceleration
25 ms-1
Starting velocity
40 0 ms-1
Final velocity
20s
B Time taken 0.1 s
30
Velocity (ms -1)
C Deceleration ________ ?
-15ms -1
20
A D
300 ms-1
Starting velocity
E
10
0 ms-1
Final velocity
5
0
Time taken 25 s
0 10 20 30 40 50 60 70 80
Time taken (s) Deceleration ________ ?
Calculate the following from the information given above: (a) Work out the total distance travelled by
the moving car (from working out the total area beneath the line graph you can work out the total
distance travelled (b) Work out the deceleration or gradient of the moving object at point E. (c) Work out
the deceleration over time of the car hitting the lamp post and the plane landing.

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Stopping distances one
National speed limits apply to all roads in the United Kingdom. The speed limit is the absolute
maximum and does not mean it is safe to d_____ at that speed irrespective of road and weather
conditions. Driving at speeds too fast for the road and traffic conditions can be dangerous. The
overall stopping distance is the sum of the distance travelled by your car, when you are reacting
to an incident and the actual d_________ travelled whilst your brakes slow and eventually stop
your car. At 70 mph, the overall stopping distance is a huge 96 metres, almost the length of a
football pitch. What factors may lead to an increase in your thinking or stopping distance ?
Stopping distances for cars in dry weather: Word bank: drive distance
Total distance
Speed Thinking distance and Stopping distance
20 mph 12 metres
6 metres
6 metres
30 mph 23 metres
14 metres
9 metres
40 mph 36 metres
24 metres
12 metres
50 mph 53 metres
38 metres
15 metres
60 mph 73 metres
55 metres
18 metres
70 mph 96 metres
75 metres
21 metres
Notes Overall stopping distances are published for cars travelling at the above speeds.
These stopping distance assume that there is good visibility, your brakes and tyres
are in good working order and that the road conditions are dry.

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Stopping distances two
The speed limit is the absolute maximum and does not mean it is safe to drive at that speed
irrespective of road and weather conditions. Your s__________ distance can be affected by road and
traffic conditions, for example a wet road surface can almost double you stopping distance. You
should always reduce your speed when the road layout or conditions presents hazards, such as
sharing the road with pedestrians, cyclists, children, motorcyclists and other c______. Driving at
night requires caution, as it is harder to see other road users. How might drinking alcohol affect your
overall stopping distance and why is there no safe limit when you are driving a car ?
Factors affecting stopping distances for cars: Word bank: stopping cars
Weather conditions Alcohol Other road users
Diagram
The weather, the amount of alcohol you drink and other road users can all affect how quickly you
Notes
can bring you car to a halt. Alcohol affects your reaction or thinking time. This is why the
government has set a legal limit of the amount of alcohol you can consume whilst driving.
Normal road conditions
24 metres
12 metres
Wet road conditions
38 metres
24 metres
12 metres
When travelling on a wet road surface, your braking distance can almost double. During heavy rain,
Notes
speed limits on motorways are reduced for safer driving.

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What is friction
Ordinary friction between objects can be thought of as arising from surface roughness.
Although two objects can appear to have relatively smooth surfaces, under the microscope,
their surfaces can be extremely rough or pitted. This unevenness causes friction between
moving objects, for example an engine piston moving inside a cylinder. Friction causes heat to
build up as an object’s atoms or molecules gain kinetic energy. Try this: rub your hands
together...do they become warm ?
Useful and unwanted friction:
Example one Example two Example three Example four
Diagram
Useful Useful Unwanted Unwanted
Friction between the Friction between the Friction between the skier The friction between
brake plate and the disc climbing axe and the ice and the ice slows down suitcase wheels and the
slows the car down keeps the ice climber the downhill skier. How ground slows down
converting the car’s pictured here from falling can you make the skies progress. How do wheel
kinetic energy into heat. to the ground. faster ? bearings reduce friction ?

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What is air resistance
Ordinary air resistance is the force that acts against anything that moves through the
atmosphere or air. Moving objects have to push past air molecules when they are moving
forward. This force becomes larger in magnitude when an object increases its speed. It can be
reduced by an object having a more aerodynamic shape, for example a sports car has a very low
profile and a smooth pointed front. When the car travels at high speeds, air resistance is kept
low. Streamlining also works when travelling through water. Explain why swimmers often
shave their hair during competition ?
Air resistance and car design:
Beetle (Top speed 200 kmhr-1) Porsche (Top speed 240 kmhr-1) 4 x 4 (Top speed 170 kmhr-1)
Diagram
Notes Overcoming air resistance at high speeds requires an aerodynamic shape. Sports cars are designed so that
their shape allows air to flow over and around their body therefore reducing air resistance. This and the fact
that they have large powerful engines allows them to achieve very high top speeds. How can you say that
the shape of the other two cars is related to their top speeds ?

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Falling objects and air resistance
As an object falls through air, it usually encounters some degree of air resistance. Air resistance
is the result of collisions of the object's leading surface with air molecules. The actual amount
of air resistance encountered by the object is dependent upon a variety of factors. To keep the
topic simple, it can be said that the two most common factors which have a direct effect upon
the amount of air resistance are the speed of the object and the cross sectional area of the
object. Therefore both increased speed and cross sectional area of a moving object results in an
increased amount of air resistance.
Falling objects and air resistance:
Start Middle End Using parachutes
Diagram 750 N
750 N
750 N
Gravity
Gravity
Gravity
Air resistance
Air resistance
Air resistance
550 N 750 N
250 N
At the start of the jump, the air resistance is low and the free faller accelerates Parachutes have a large
downwards. As his speed increases, the air resistance increases, slowing his cross sectional profile
acceleration. Eventually the air resistance force will be equal and opposite to which increases the air
the downward force due to gravity. At this point the free faller’s speed remains resistance. This lowers
constant. your descent speed.

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Understanding terminal velocity
Why does an object which is falling and encountering air resistance eventually reach terminal
velocity ? As an object falls, it picks up speed. The increase in speed leads to an increase in the
amount of air resistance. Eventually, the force of air resistance becomes large enough to balance the
force of gravity. At this instant in time, the net force on the falling object is 0 Newtons, therefore the
object stops accelerating and the objects velocity remains constant. The velocity at which this
happens is called the ‘terminal velocity.’ Which object would have a lower terminal velocity when
falling through air, a 10 g feather or a 10 g coin ?
Terminal velocity:
Terminal velocity Falling with parachute Falling without parachute
Diagram
C
A
Gravity
60
60
45
45
30
30
Velocity (ms-1)
Velocity (ms-1)
Air resistance
B
15
15
0
0
0 Time (s) Time (s)
50 100 0 50 100
Notes Free falling, without a Falling with parachute: Speed Falling without parachute: Speed
parachute, gravity accelerates increases reaching terminal increases reaching terminal
you to Earth’s surface reaching velocity at A, where parachute velocity at C, where the force of
a terminal velocity of about deployment reduces speed air resistance becomes large
50 ms-1. Nothing beats the reaching a lower terminal velocity enough to balance the force of
at B. gravity.
sensation of free falling !

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Newton and forces
Newton was born December 25th 1642. He was admitted in June 1661 to Trinity College, Cambridge.
Between 1664 and 1666, Newton lay the groundwork of his theory of calculus, laws of m______, theory of
colour, and theory of universal gravitation. It is during these few years that nearly all of Newton's lifetime
scientific achievements took shape. Shortly thereafter, he designed and constructed the first reflecting
telescope. Newton's key insight of 1666, namely that gravity, the force felt here on Earth is the same force
that held the planets in their orbits around the Sun. Newton developed in detail these ideas, providing a
theoretical framework for the Laws of planetary motion. Newton made numerous discoveries in the field of
optics, especially with respect to light and colours. He was knighted in 1705 and died on 20th March 1727.
Sir Isaac Netwon and Newton’s laws: Word bank: motion
Newton Newton’s Laws of Motion
Newton’s first Law:
Diagram
Newton’s first law states: ‘An object in motion tends to stay in
motion, and an object at rest tends to stay at rest, unless the
object is acted upon by an outside force.’
Newton’s second Law:
Newton’s second law states that ‘Acceleration = force/mass.’
This law relates the force exerted on an object, its mass and
resulting acceleration.
Newton's ideas were written
Notes
between 1684 and 1686 and Newton’s third Law:
published by Edmond Halley, Newton’s third law states that: ‘Every action has an equal
of cometary fame. His thesis
and opposite action.’ This law relates how if you’re falling to
was titled: Philosophiae
Earth, the Earth is also falling toward you !
Naturalis Principia Mathematica

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Newton’s first law
Newton’s first law states “An object in motion tends to stay in motion, and an object at rest
tends to stay at rest, unless the object is acted upon by an outside force.” For example, an
object at r_______ will stay at rest unless a force is applied to it. If it is moving, it will keep on
moving at a constant speed and in a straight line. Name two types of forces acting on a
stationary car: Draw a diagram of these forces...are they equal in size ?
Newton’s first law: Word bank: rest
Example one Example two Example three
Diagram
Astronaut at rest: At rest: Constant speed:
Notes
In this example, the astronaut The archer exerts a force by As the space probe gains speed, due
will remain motionless unless using his skeletal muscle on the to the pull of gravity, friction due to
an outside force acts upon him bow and arrow which is equal in air resistance increases, so that the
during his space walk. How size but opposite to the elastic two forces are equal, but opposite.
would the astronaut make pull of the bow. What will The probe stops accelerating and
himself go forwards ? happen when he lets go ? travels at a constant speed.

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Newton’s second law one
Newton’s second law states that Acceleration = Force/Mass or F =ma
Acceleration = Force (N)/ Mass (kg) Units for acceleration = m/s2
When the forces acting on an object is unbalanced, the resultant force causes the object to
change its speed or velocity. It accelerates or decelerates. How fast it accelerates or decelerates
depends on:
Mass (the more mass an object has for the same force, the less it accelerates)
Resultant Force (the greater the force acting on an object with the same mass, the faster it will accelerate)
Newton’s second law:
Example one Example two Example three
Diagram
1N
1 kg
a = 1 m/s2
Having the biggest engine and The standard definition of a Buses are slow, although they
Notes
the lightest car gives formula Newton: One Newton is have a very powerful engine
one drivers and their teams defined as the force which will delivering a lot of force, their
like Ferrari an advantage over give an object with the mass of mass is huge when compared to
1 kg, an acceleration of 1 m/s2.
the other competitors. that of a car.

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Newton’s second law two
Working out the acceleration of a moving object with a known fixed mass and a known force
acting upon it is easy. Newton’s second law tell us that the acceleration of an object is equal to
force divided by its mass. Work out the acceleration of the different moving vehicles which all
have different masses and resultant forces acting upon them...explain why a lorry is slow to
accelerate when compared to a bullet or even a cyclist ?
Acceleration = Force (N)/ Mass (kg) Units for acceleration = m/s2
Working out acceleration:
Lorry Bullet Motorbike Cyclist
Diagram
Force 90,000 N 20 N 12000 N 600 N
Mass 30,000 kg 0.1 kg 800 kg 80 kg
Acceleration = force/mass Acceleration = force/mass Acceleration = force/mass Acceleration = force/mass
(m/s2)
_______________________ ? _______________________ ?
a= 90,000N/30,000 kg _______________________ ?
___________m/s2 ___________m/s2
= 3 m/s2 ___________m/s2

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Newton’s third law
Newton’s third law states “Every action has an equal and opposite re - action”
Think about this. If you are falling towards Earth, then Newton’s third law states that there
must be an e_______ and opposite reaction. Does the Earth move upwards towards you falling
downwards ? Well yes it does, but its mass is huge, so the effect cannot be measured or seen.
Another example, when you shoot a gun, the f____ that propels the bullet forwards also pushes
you backwards a little. Again there is a great difference between the mass of a bullet and the
person, but the effect can be seen. Why in movies do we know that they exaggerate this effect ?
Newton’s third law: Word bank: equal force
Example one Example two Example three
Diagram
Gun shot: Free falling: Rocket:
Notes
The force pushes you As you free fall, the Earth The thrust of the rocket’s engines
backwards, as the bullet moves experiences an equal and opposite pushes against the Earth. As the
forwards from the gun barrel. reaction, although because of rocket moves out to space, Earth
Movies exaggerate this a great Earth’s huge mass it can’t be undergoes an equal and opposite
deal for effect ! observed reaction.

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Kinetic energy one
Kinetic energy requires us to relate the velocity and mass of a moving object. Understanding the
kinetic e________ of a car at different speeds, helps us understand why we have speed limits on the
streets of our towns and villages. If a child is hit at 30 mph (approx 15 ms-1) the child has a 80%
chance of surviving. If the same car hits the same child at 40 mph, the child has only a 20% chance
of surviving. This is because we square the speed to work out the energy of the car moving at a
certain speed. A car travelling at 40 mph imparts 10squared or 100 times the energy into a child’s body
compared to a car travelling at 30 mph. Work out the kinetic energy of the car at different
velocities...explain why around schools the speed limit is 20 mph ?
Kinetic energy: Word bank: energy
Car at 10 ms-1 Car at 15 ms-1 Car at 20 ms-1 Car at 30 ms-1
Diagram 30mph 60mph
40mph
20mph
10 ms-1 (approx 20 mph) 15 ms-1 (approx 30 mph) 20 ms-1 (approx 40 mph) 30 ms-1 (approx 60 mph)
Speed
Mass 800 kg 800 kg 800 kg 800 kg
½ x mass x (velocity)2 ½ x mass x (velocity)2 ½ x mass x (velocity)2 ½ x mass x (velocity)2
Kinetic
energy (J)
_______________________ ? _______________________ ?
½ x 800 kg x (10 ms-1)2 _______________________ ?
___________J ___________J
= 40,000 J ___________J ? ?
?

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Kinetic energy two
All moving objects have kinetic energy. Kinetic energy requires us to relate the velocity and
mass of a moving object. Therefore kinetic energy of a moving objects depends on its mass and
velocity. If an object like a p_______ with a large mass travels at low speeds, it has a large
kinetic energy. Also, if an object like a bullet with a low mass travels at very high speeds, it too
will have a high kinetic energy. Work out the kinetic energy of the following moving vehicles
which all have the same velocity...explain why being hit by a lorry at 20 ms-1 is much more
likely to kill you than when you are hit by a cyclist at 20 ms-1 ?
Kinetic energy: Word bank: plane
Lorry Cyclist Car Plane
Diagram
20 ms-1 20 ms-1 20 ms-1 20 ms-1
Speed
Mass 30,000 kg 80 kg 800 kg 350,000 kg
½ x mass x (velocity)2 ½ x mass x (velocity)2 ½ x mass x (velocity)2 ½ x mass x (velocity)2
Kinetic
energy (J)
_______________________ ? _______________________ ?
½ x 30,000 kg x (20 ms-1)2 _______________________ ?
___________J ___________J
= 6,000,000 J ___________J ? ?
?

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Kinetic energy three
All moving objects have kinetic energy. Kinetic energy requires us to relate the velocity and
mass of a moving object. Therefore kinetic energy of a moving objects depends on its mass and
velocity. Bullets kill you, not because of their m____, but because of their very high velocities.
A tanker can crush you to death even if it moves at 0.1 ms-1 because it has a huge mass. A
asteroid impacting with Earth, may cause climate change and mass extinction, because it has a
high mass and velocity. Work out the kinetic energy of the different moving objects which have
different velocities and masses...explain why a bullet can kill you, despite its low mass ?
Kinetic energy: Word bank: mass
Bullet at 500 ms-1 Tanker at 0.1 ms-1 Car at 30 ms-1 Meteor at 3000 ms-1
Diagram 60mph
500 ms-1 0.1 ms-1 30 ms-1 3000 ms-1
Speed
Mass 0.1 kg 5,000,000 kg 800 kg 100,000 kg
½ x mass x (velocity)2 ½ x mass x (velocity)2 ½ x mass x (velocity)2 ½ x mass x (velocity)2
Kinetic
energy (J)
_______________________ ? _______________________ ?
½ x 0.1 kg x (500 ms-1)2 _______________________ ?
___________J ___________J
= 25,000 J ___________J ? ?
?

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Kinetic energy four
An unbalanced force provided by a combustion engine found in cars, trains or lorries can accelerate a
moving vehicle forwards increasing its kinetic energy. During a car journey, c_________ energy in
the fuel is transformed to kinetic energy. The greater the speed of the car, the more fuel the engine
uses. Some of the chemical energy is wasted overcoming internal f_______ and air resistance. When
a car slows, the kinetic energy is converted into heat energy by the brakes. The force of friction
causes this energy transfer. Why do lorries and buses consume more fuel than cars and motorbikes ?
Work done: Word bank: chemical friction
Converting chemical energy into kinetic energy Notes
When we combust fuels like
octane with oxygen, energy in the
form of heat and kinetic energy is
released. New substances are also
produced including carbon dioxide
2C8H18 + 25O2 CO2 + 18H2O
and water.
Octane Oxygen Carbon dioxide Water
A car over a journey of 80 minutes
4000,000
80,000
will have different kinetic energies.
Chemical energy (J)
Since its mass doesn’t change this
Kinetic energy (J)
60,000 3000,000
B
is linked to its velocity. As the
40,000 2000,000
C
A journey proceeds, chemical energy
F gradually reduces as petrol is
20,000 1000,000
E
combusted in the engine to provide
D
0 0
forward motion and overcome
0 10 20 30 40 50 60 70 80
internal friction and air resistance.
Time taken (minutes)

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Work done one
Energy or a force is required to do work like lifting, pulling, pushing and stretching. In science,
work is done if a force pushes, pulls, stretches or lifts an object with a mass. The amount of
work done is always measured in joules. The result of doing work, means that an objects gains
the following types of energy:
Kinetic energy Gravitation potential energy Heat energy Units for work done = Joules
Look at these examples and determine what kind of energy has been given to the object as a
result of doing work ?
Work done:
Pushing Pulling Lifting Stretching
Pushing: When you push a car or an object, the car starts to move. Energy has been transferred to the car as
kinetic energy. Pulling: When you pull the rope, the rope will start to move. Energy has been transferred as
kinetic energy. Lifting: When a object is lifted above ground level by using a force, the gravitational potential
energy of the object starts to increase. Stretching: If you stretch something it gains elastic potential energy.
Repeated stretching, because of friction between the molecules transfers energy into heat energy.

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Work done two
The amount of work done is equal to the amount of energy transferred and is always measured in
joules. A large force t_________ more energy and the further the distance it moves, the more energy
is transferred. Therefore the amount of work done is the force multiplied by the distance moved.
Work done = force (N) x distance moved in the direction of the force (m) Units for work done = Joules
Look at these examples and determine what kind of energy has been given to the object as a
result of doing work ?
Work done: Word bank: transfers
Example one Example two Example three Example four
Lifting
Example five Example six Example seven Example eight

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Work done three
The amount of work done is worked out using the following equation:
Work done = force (N) x distance moved in the direction of the force (m) Units for work done = Joules
When we are calculating, the amount of w_____ done a body does to lift a mass vertically upwards
against gravity, this work done is transferred into gravitational potential energy. When we move
sides ways, no work is done because our bodies are not getting any higher.
Look at these examples and determine the amount of work done. Remember vertical distance only !
Work done: Word bank: work
Example one Calculation Example two Calculation
A pulley is a device A man weighing
which can lift heavy 600 N walks up four
loads. The pulley in flights of stairs.
the diagram, lifts a These stairs climb a
Vertical distance 20 m
Vertical distance 10 m
100 N weight through total vertical distance
a vertical distance of of 20 metres. Work
10 metres. Work out out the work done
the work done using using the above
the above formula ? formula ?
Remember the formula: Remember the formula:
Work done = force x Work done = force x
100 N distance moved distance moved
600 N

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Work done four
Look at these examples and determine the amount of work done. Use the equation below and
give your answers in joules or kilojoules ?
Work done = force (N) x distance moved in the direction of the force (m) Units for work done = Joules
Work done:
Problem one Problem two Problem three Problem four
Diagram
Car (8000 N) climbing A lift carrying 4 people A man (600 N) climbing A plane weighing
an alpine pass that is over 50 m with a total the stairs ascending a 3,500,000 N climbing to
2000 m high. weight of 15,000 N. vertical height of 25 m. 10 km above sea level.
Weight (N) 8,000 N 15,000 N 600 N 3,500,000 N
Vertical 2000 m 50 m 25 m 10,000 m
height (m)
Calculation 8000 N x 2000 m
Answer (J) 16,000,000 Joules ______________ ? ________________ ? _________________?

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Extension questions and homework
1: Define the following terms: Force, Newton, Speed, Velocity, Acceleration & Deceleration.
2: Look at the velocity time graph. Complete the table.
Question Answer
B At which point is the cycle travelling at constant velocity ?
20
At which points is the cyclist accelerating ?
15
At which point is the cycle not moving ?
V e lo c ity ( m s -1 )
A C
10 At which point is the cycle decelerating ?
F What is the cycle’s highest velocity ?
5
E At A what is the average acceleration of the cyclist over 10 seconds.
D
0
At B between 10 and 30 seconds what distance does the cycle travel ?
0 10 20 30 40 50 60 70 80
Time taken (s) How long in seconds is the cycle stationary for ?
3: Answer and explain the following:
a) A machine gun recoils when it is fired.
b) During a spacewalk, an astronaut begins to drift away from the space shuttle. How can he return using an
aerosol spray
c) When you walk forwards, you can move the planet Earth backwards.
d) Give three examples of unbalanced and balanced forces in action. Draw one of each.
e) Speedboats have sharper front ends than a ferry or a barge.
f) Sliding down a rope can burn the skin on your hand.

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4: Answer the following questions (Take g = 10 m/s2 = 10 N/kg where necessary.)
(a) A car travels 200 m in 5 seconds: What is its average speed.
(b) A car accelerates from 5 ms-1 to 25 ms-1 in 10 seconds. What is its acceleration.
(c) Sketch a velocity-time graph of you walking to a bus stop for 2 minutes at a speed of 5 km/hr, catching the bus
which then travels at 50 km/hr for 10 minutes, getting off and then running to school at 9 km/hr for 3 minutes.
5: The table gives some data for a grand prix motor-bike race at the start.
Speed (ms-1) 0 10 20 28 36 49 64 65 65 65
Time (s) 0 1 2 3 4 5 6 7 8 9
(a) Plot a velocity-time graph.
(b) What was the average acceleration between (i) 2-3 s (ii) 4-5s (iii) 8-9s
6: Answer the following questions.
(a) The canary wharf tower is 400 metres high. Some jumps off. How long to they have to live.
(b) Explain why parachutists and snowflakes do not fall with a constantly accelerating motion.
(c) A car accelerates from rest (0 ms-1) to a final velocity of 10 ms-1 for 12 seconds. Calculate the final velocity.
7: A car is approaching a set of traffic lights. Three forces are acting upon it: (i) The forward force of the engine. 400
N (ii) The backward force of the brakes; 1200 N. (iii) Air resistance 200 N
(a) Draw a diagram to show the forces acting on the car.
(b) What is the unbalanced force acting on the car.
(c) If the car’s mass is 650 kg work out its deceleration. Show your working out.
(d) What is the car’s kinetic energy converted into as it slows down.

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8: Answer the following questions:
(a) Find out the thinking and stopping distance of a car travelling at 60mph. (b) What conditions may affect the
braking distance. (c) Why is there a legal maximum on the amount of alcohol you can drink, before driving a car.
9: Answer the following questions:
(a) A large bus carrying many passengers and a small car with just the driver are travelling at the same velocity
along a main road. The traffic lights ahead turn red. Explain why the bus needs better brakes and a better braking
force than the small car.
(b) At the traffic lights, a lorry, bus, cyclist and motorbike accelerate when the lights turn back to green. Work out
the acceleration of all from the following information. Which is the fastest...explain this.
Diagram
Force 90,000 N 70,000 N 12000 N 600 N
Mass 30,000 kg 20,000 kg 800 kg 80 kg
10: Look at these graphs. They represent the way different quantities might differ when a coin is dropped to the ground.
Graph yA yC yD
yB
time (s) time (s)
time (s) time (s)
Which graph represents: (a) The weight of the coin as it falls. (b) The resultant force acting on the coin. (c) The
velocity of the coin as it falls. (d) The force of air resistance on the coin as it falls.
Go to google.co.uk and find out about Newton’s life and his three laws of motion.