Download P3 Booklet FINAL - Highfields School, Wolverhampton

HIGHFIELDS
SCHOOL
Physics Department
OCR GCSE Physics
P3 – Forces for Transport
Student Support Booklet
Equations
Take the value of g to be 10 m/s2 or 10 N/kg unless stated otherwise in the question.
P3 – Key Words
ABS
Braking system known as advance braking system which
helps to control a skidding car
Accelerate
An object accelerates if it speeds up
Acceleration
A measure of how quickly the speed of a moving object
changes (if speed is in m/s then acceleration is in m/s2)
Air bags
Cushions which inflate with gas to protect people in a
vehicle accident
Air resistance
The force exerted by air to any object passing through it
Average speed
Total distance travelled divided by the total time taken
for a journey
Balanced forces
Forces acting in opposite directions that are equal in size
Braking distance
Distance travelled while a car is braking.
Conservation of energy Principle stating that energy can neither be created nor
destroyed, but can be transferred from one form into
another
Crash barrier
Barrier used to prevent vehicles crossing from one
carriageway to the other, causing a head-on collision.
Crash testing
Deliberately crashing vehicles and analysing results to
improve car safety
Cruise control
System that automatically controls the speed of a
vehicle
Crumple zones
Areas of a car that absorb the energy of a crash to
protect the centre part of the vehicle
Decelerates
An object decelerates if it slows down.
Deceleration
A measure of how quickly the speed of a moving object
decreases
Distance-time graph
A plot of the distance moved against the time taken for
a journey
Drag
Energy losses caused by the continual pushing of an
object against the air or a liquid
Dummies
Used in crash testing to learn what would happen to the
occupants in the event of a crash
Electric cars
Cars running on solar power or batteries
Electric windows
Windows that can be opened or closed at the push of a
button
Energy
The ability to ‘do work’ – the human body needs energy
to function
Escape lane
Rough surfaced uphill path adjacent to a steep downhill
road enabling vehicles with braking problems to stop
Force
Fossil fuels
Free-fall
Friction
Gradient
Gravitational field
strength
Gravitational potential
energy
Gravity
Hybrid cars
Impact
Instantaneous speed
Joule
Kilogram (kg)
Kinetic energy
Linear
Magnitude
Mass
Momentum
Net force
Newtons
Paddle shift controls
Power
Primary safety features
Reaction time
Relative velocity
Resultant force
Safety cage
safely
A push or a pull which is able to change the velocity or
shape of a body
Fuels such as coal, oil and natural gas
A body falling through the atmosphere without an open
parachute
Energy losses caused by two or more surfaces rubbing
against each other
Rate of change of two quantities on a graph; change in
y divided by change in x
The force of attraction between two masses
The energy a body has because of its position in a
gravitational field e.g. an object
An attractive force between objects (dependent on
their masses and the distance between them)
Cars powered by electric batteries which also have fuel
engines
Collision between two moving objects or a moving
object and a stationary object
The speed of a moving object at one particular moment
Unit of work done and energy
Unit of mass
The energy that moving object have
A line of constant gradient on a graph
Size of something
Describes the amount of something, measured in
kilograms (kg)
The product of mass and velocity
Same as resultant force
Unit of force (abbreviated to N)
Controls attached to the steering wheel of a car so that
the driver can use them without taking their eyes off the
road.
Rate of transfer of energy, units are Watts (W)
Help to prevent a crash e.g. ABS brakes, traction control
The time it takes for the driver to step on the brake after
seeing an obstacle
Vector difference between the velocities of two objects
The combined effect of forces acting on an object
A car’s rigid frame that protects occupants in a roll-over
accident
Seat belts
Secondary safety
features
Side impact beams
Speed
Speed camera
Speed-time graph
Stopping distance
Streamlining
Terminal speed or
velocity
Thinking distance
Traction control
Tread
Unbalanced forces
Velocity
Watt
Weight
Work done
Harness worn by occupants of motor vehicles to prevent
them from being thrown about in a collision
Protect occupants in the event of a crash e.g. crumple
zones, air bags, seatbelts
Bars in the side of a car to lessen the amount of
bodywork distortion inside the car
How fast an object travels: speed = distance ÷ time
Device used to measure the speed of a moving vehicle
A plot of how the speed of an object varies with time
Sum of the thinking and braking distances
Shaping an object to reduce resistance to motion
The top speed reached when drag matches driving
force
Distance travelled while the driver reacts before braking
Helps limit tyre slip in acceleration on slippery surfaces
Pattern on part of tyre that comes into contact with
road surface to provide traction
Forces acting in opposite directions that are unequal in
size
How fast an object is travelling in a particular direction;
velocity = displacement ÷ time
A unit of power, 1W = 1 joule of energy being transferred
per second
The force of gravity acting on a body
Product of the force and distance moved in the
direction of the force
Module P3: Forces for Transport
P3a: Speed
Transport and road safety provide the context for this module. The abilities to describe and measure motion are used in the
treatment of issues involving everyday transport. Speed is studied in this item; how it can be measured and calculated and how
distance and time can be graphically represented.
GRADE G - D
Use the equation:
to include change of units from km
to m.
Understand why one type of speed
camera takes two photographs:
• a certain time apart
GRADE C
Interpret the relationship between
speed, distance and time including:
• increasing the speed, which
increases the distance travelled in the
same time
GRADE B – A*
Interpret the relationship between
speed, distance and time to include
the effect of changing any one or
both of the quantities.
Use the equation, including a change
of subject and/or units:
• increasing the speed reduces the
time needed to cover the same
distance.
Use the equation, including a change
of subject:
• when the vehicle moves over
marked lines a known distance
apart on the road.
Understand how average speed
cameras work.
Draw and interpret qualitatively
graphs of distance against time.
Describe and interpret the gradient
(steepness) of a distance-time graph
as speed (higher speed gives steeper
gradient).
Draw and interpret graphs of distance
against time:
• qualitatively for non-uniform speed
• calculations of speed from the
gradient of distance-time graph for
uniform speed.
Targets for
Improvement
P3a Activities
Time (s)
Distance
(m)
Distance
Distance
(m)
(m)
Distance
(m)
1. Describe the motion of an object in each of the following
distance-time graphs:
Time (s)
Time (s)
2. Work out the speed on the graph at each stage below (show
your working out):
Stage 1: ………………………………………………………………………………………………
Stage 2: ………………………………………………………………………………………………
Stage 3: ………………………………………………………………………………………………
Stage 4: ………………………………………………………………………………………………
3. Answer the following calculations:
a. A plane on a short internal flight covers 400 km in 30 minutes.
(i) What is the average speed in km/hour?
…………………………………………………………………………………………………………...
…………………………………………………………………………………………………………...
…………………………………………………………………………………………………………...
(ii) What is the speed in m/s?
…………………………………………………………………………………………………………...
…………………………………………………………………………………………………………...
…………………………………………………………………………………………………………...
b. A car speeds up from 15 m/s to 30 m/s in 20 s. What is the distance travelled?
…………………………………………………………………………………………………………...
…………………………………………………………………………………………………………...
…………………………………………………………………………………………………………...
…………………………………………………………………………………………………………...
c. Find the speed in m/s of a walker who travels 12 km in 2.5 hours.
…………………………………………………………………………………………………………...
…………………………………………………………………………………………………………...
…………………………………………………………………………………………………………...
d. How long does it take light to travel from the Sun to the Earth (150 000 000 km) at
a speed of 300 000 km/s? Provide the answer in minutes and seconds.
…………………………………………………………………………………………………………...
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…………………………………………………………………………………………………………...
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Module P3: Forces for Transport
P3b: Changing Speed
In this item the idea of acceleration is developed. The concept of velocity is introduced here, and is developed further in P5.
Accelerations (involving the change in speed) of cars can be used and graphically illustrated and studied.
GRADE G - D
GRADE C
GRADE B – A*
Describe the trends in speed
and time from a simple speedtime graph:
• horizontal line – constant
speed
• straight line positive gradient
– increasing speed
• straight line negative
gradient – decreasing speed.
Describe, draw and interpret
qualitatively, graphs of speed
against time for uniform
acceleration to include:
• greater acceleration shown
by a higher gradient
• the significance of a positive
or negative gradient
• calculations of distance
travelled from a simple speedtime graph for uniform
acceleration.
Describe, draw and interpret
graphs of speed against time
including:
• quantitatively for uniform
acceleration
• calculations of distance
travelled from a speed-time
graph for uniform acceleration
• calculations of acceleration
from a speed-time graph for
uniform acceleration
• qualitative interpretation of
speed-time graphs for nonuniform acceleration.
Targets for
Improvement
Recognise that acceleration
involves a change in speed
(limited to motion in a straight
line):
• speeding up involves an
acceleration
• slowing down involves a
deceleration
• greater change in speed (in
a given time) results in higher
acceleration.
Recall that acceleration is
measured in metres per
second squared (m/s2).
Use the equation:
when given the change in
speed.
Recognise that direction is
important when describing the
motion of an object.
Understand that the velocity of
an object is its speed
combined with its direction.
Describe acceleration as
change in speed per unit time
and that:
• increase in speed results from
a positive acceleration
• decrease in speed results
from a negative acceleration
or deceleration.
Explain how acceleration can
involve either a change:
• in speed
• in direction
• in both speed and direction.
Interpret the relationship
between acceleration,
change of speed and time to
include the effect of changing
Use the equation including
any one or two of the
prior calculation of the change quantities.
in speed:
Use the equation, including a
change of subject:
Recognise that for two objects
moving in opposite directions
at the same speed, their
velocities will have identical
magnitude but opposite signs.
Calculate the relative velocity
of objects moving in parallel.
P3b Activities
Time (s)
Velocity
(m/s)
Velocity
(m/s)
Velocity
(m/s)
1. Describe motion shown in each of the following velocity-time
graphs:
Time (s)
Time (s)
2. Sketch a velocity-time graph in the box below to show a car
that starts from rest. The car then increases acceleration for 15
seconds before travelling at a steady speed of 14 m/s for 180
seconds. The car then decelerates at a constant rate before
coming to a stop after a total of 240 seconds of travel.
3. Complete the following calculations:
a) A cyclist accelerates from 10 to 20m/s in 5 seconds. What is her
acceleration?
……………………………………………………………………………………
……………………………………………………………………………………
……………………………………………………………………………………
b) A car accelerates from 15 to 30m/s with an acceleration of
2m/s2. How long did this take?
……………………………………………………………………………………
……………………………………………………………………………………
……………………………………………………………………………………
c) A ball is dropped and accelerates downwards at a rate of
10m/s2 for 15 seconds. How much will the ball’s velocity increase
by?
……………………………………………………………………………………
……………………………………………………………………………………
……………………………………………………………………………………
4. What is the distance travelled in the first 40 seconds of Jessica’s
training run?
Module P3: Forces for Transport
P3c: Forces and Motion
Before taking your driving test you need to pass a theory test. Part of this involves driving safely and knowledge of car stopping
distances. Driving fast may be tempting but stopping safely is more important. In this item we start to understand the effects of
forces on braking and the factors which affect stopping distances. The experiments using elastics, light gates and trolleys allow
the opportunity to collect and analyse scientific data using ICT tools and the interpretation of the data using creative thought
to develop theories. Work on stopping distances provides the opportunity to discuss how and why decisions about science and
technology are made, including ethical issues and the social, economic and environmental effects of such decisions.
GRADE G - D
Recognise situations where
forces cause things to:
• speed up
• slow down
• stay at the same speed.
Use the equation:
GRADE C
Describe and interpret the
relationship between force,
mass and acceleration in
everyday examples.
Use the equation, including a
change of subject and the
need to previously calculate
the accelerating force:
Use the equation, including a
change of subject:
force = mass × acceleration
force = mass × acceleration
force = mass × acceleration
when given mass and
acceleration.
GRADE B – A*
Targets for
Improvement
Describe thinking distance as:
• the distance travelled
between the need for braking
occurring and the brakes
starting to act.
Describe braking distance as:
• the distance taken to stop
once the brakes have been
applied.
Describe stopping distance as:
• thinking distance + braking
distance.
Explain how certain factors
may increase thinking
distance:
• driver tiredness
• influence of alcohol or other
drugs
• greater speed
• distractions or lack of
concentration.
Explain how certain factors
may increase braking
distance:
• road conditions
• car conditions
• greater speed.
Calculate stopping distance
given values for thinking
distance and braking distance. Interpret data about thinking
distances and braking
Explain why thinking, braking
distances.
and stopping distances are
significant for road safety.
Explain the implications of
stopping distances in road
safety:
• driving too close to the car in
front (i.e. inside thinking
distance)
• speed limits
• road conditions.
Explain qualitatively everyday
situations where braking
distance is changed including:
• friction
• mass
• speed
• braking force.
Draw and interpret the shapes
of graphs for thinking and
braking distance against
speed.
Explain the effects of increased
speed on:
• thinking distance – increases
linearly
• braking distance – increases
as a squared relationship e.g. if
speed doubles braking
distance increases by a factor
of four, if speed trebles braking
distance increases by a factor
of nine.
P3c Activities
1. Put the equation:
Force = mass x acceleration
into a formulae triangle and label with the correct units.
2. Use the formulae triangle to complete the following calculations:
a) A force of 2000N is applied to push a mass of 500kg. How quickly does it
accelerate?
…………………………………………………………………………………………………………
…………………………………………………………………………………………………………
…………………………………………………………………………………………………………
b) A force of 6000N acts on a car to make it accelerate by 1.5m/s2. How heavy is
the car?
…………………………………………………………………………………………………………
…………………………………………………………………………………………………………
…………………………………………………………………………………………………………
c) A car accelerates at a rate of 3.5m/s2. If it has a mass is 750kg how much driving
force is the engine applying?
…………………………………………………………………………………………………………
…………………………………………………………………………………………………………
…………………………………………………………………………………………………………
3. Look at the two vehicles pictured. If they have the same force, which will
accelerate faster and why? (Try to describe the relationship in as much detail as you
can).
…………………………………………………………………………………
…………………………………………………………………………………
…………………………………………………………………………………
…………………………………………………………………………………
4. “There is a proportional relationship between force and acceleration.”
What does this statement mean? .........................................................................................
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5. What factors affect thinking distance and braking distance? Complete the table
below:
Thinking Distance
Braking Distance
6. Describe the relationship between (a) thinking distance (b) braking distance and
speed?
a)....................................................................
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b)....................................................................
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.......
Module P3: Forces for Transport
P3d: Work and Power
Work is done whenever a force moves something. Transport, by its nature, is always moving and energy is being transferred all
the time. In this item we will learn about power and the energy we use to provide it. Different power ratings, fuel consumption,
engine size costs and associated environmental issues about car use can be used to develop the skills of presenting
information, developing an argument and drawing a conclusion using scientific terms. This also provides the opportunity to
discuss how scientific knowledge and ideas change over time.
GRADE G - D
GRADE C
Recall everyday examples in
which work is done and power
is developed to include:
• lifting weights
• climbing stairs
• pulling a sledge
• pushing a shopping trolley.
Use the equation:
Describe how energy is
transferred when work is done.
Use the equation, including a
change of subject:
Understand that the amount of
work done depends on:
• the size of the force in
newtons (N)
• the distance travelled in
metres (m).
work done = force × distance
weight = mass × gravitational
field strength
GRADE B – A*
Use the equation, including a
change of subject:
weight = mass × gravitational
field strength
Use the equation:
work done = force × distance
then use the value for work
done in the power equation
below.
Targets for
Improvement
Recall that the joule is the unit
for both work and energy.
Use the equation:
work done = force × distance
Describe power as a
measurement of how quickly
work is being done.
Recall that power is measured
in watts (W).
Recognise that cars:
• have different power ratings
• have different engine sizes
and these relate to fuel
consumption.
Use the equation:
Interpret fuel consumption figures
from data on cars to include:
• environmental issues
• costs.
Use the equation, including a
change of subject:
when work has been
calculated.
Use and understand the
derivation of the power
equation in the form:
power = force × speed
P3d Activities
1. Circle the two things needed for work to be done:
Distance
Acceleration
Time
Force
Velocity
Mass
2. Which of these are examples of doing work?
a) A ball rolling across a playground
b) A parent picking up a baby.
c) A lift going up a block of flats.
d) Someone sawing a piece of wood.
e) Standing at a bus stop with a bag on your back.
3. Complete the following table:
Mass (kg)
60
Weight (N)
750
1.5
4. Complete the following calculations:
a) Jane is stacking a food shelf with tins, each weighing 15N. When she has put 16
tins on the shelf she calculates that she has done 360J of work. How high is the shelf?
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b) The brakes in a car produce a force of 9000N and the car has to lose 450 000J of
kinetic energy to come to a complete stop. What is the braking distance?
....................................................................................................................................................
....................................................................................................................................................
....................................................................................................................................................
c) A boy weighing 550N runs up the stairs,
(i) in 5 seconds, and then (ii) in 10 seconds.
The vertical height of the stairs is 5m. What is his power output in each case?
....................................................................................................................................................
....................................................................................................................................................
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5. Show that the work done equation and power equation can be combined to
derive: power = force x speed
6. Match up each variable with the correct units:
Power
metre, m
Work Done
Watt, W
Force
Joule, J
Distance
Metres per second, m/s
Speed
Newton, N
7. Why do more powerful cars have a greater fuel consumption? What are the
economic and environmental impacts of having a greater fuel consumption?
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Module P3: Forces for Transport
P3e: Energy on the Move
Transport is essential to modern life whether it be bus, train, tram, bicycle, walking or car. All these need a source of energy
which is transferred to kinetic energy. Some vehicles use more fossil fuels than others and this has implications for cost, pollution
in our cities and future energy reserves. Other vehicles may use bio-fuels or solar power which are renewable energy sources.
GRADE G - D
Understand that kinetic energy
(KE) depends on the mass and
speed of an object.
Recognise and describe
(derivatives of) fossil fuels as
the main fuels in road
transport:
• petrol
• diesel.
Recall that bio-fuels and solar
energy are possible
GRADE C
Use and apply the equation:
1
𝐾𝐸 = 𝑚𝑣 2
2
GRADE B – A*
Use and apply the equation:
1
𝐾𝐸 = 𝑚𝑣 2
2
including a change of subject.
Apply the ideas of kinetic
energy to:
• relationship between braking
distances and speed
• everyday situations involving
objects moving.
Describe arguments for and
Explain how bio-fuelled and
against the use of battery
solar powered vehicles:
powered cars.
• reduce pollution at the point
of use
Explain why electrically
• produce pollution in their
powered cars do not pollute at production
the point of use whereas fossil
• may lead to an overall
fuel cars do.
reduction in CO2 emissions.
Targets for
Improvement
alternatives to fossil fuels.
Recognise that battery driven
cars need to have the battery
Describe how electricity can
recharged:
be used for road transport, and • this uses electricity produced
how its use could affect
from a power station
different groups of people and • power stations cause
the environment:
pollution.
• battery driven cars
• solar power/cars with solar
Explain why we may have to
panels.
rely on bio-fuelled and solar
powered vehicles in the future.
Draw conclusions from basic
Interpret data about fuel
data about fuel consumption,
consumption, including
including emissions (no recall
emissions.
required).
Recognise that the shape of a
moving object can influence
its top speed and fuel
consumption:
• wedge shape of sports car
• deflectors on lorries and
caravans
• roof boxes on cars
• driving with car windows
open.
Explain how car fuel
consumption figures depend
on:
• energy required to increase
KE
• energy required to do work
against friction
• driving styles and speeds
• road conditions.
Evaluate and compare data
about fuel consumption and
emissions.
P3e Activities
1. Rearrange the equation for KE to make (i) mass and (ii) velocity the subject.
(i) making mass the subject:
(ii) making velocity the subject:
2. Complete the following calculations:
a) A 70 kg skydiver falls with a terminal velocity of 50 m/s. How much Kinetic Energy
does he have?
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b) A shark swims with a velocity of 10 m/s and has 50 kJ of Kinetic Energy. What is its
mass?
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c) An 8 g bullet is fired from a gun where it gains 490 J of kinetic energy. How fast is it
moving?
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3. Which factor – mass or velocity – has the greatest effect on the kinetic energy of a
moving object? Use the data below and explain in as much scientific detail as you
can using key terminology.
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4. What are the advantages and disadvantages of using electric cars?
Advantages
Disadvantages
5. What factors can affect the top speed of a car and its fuel consumption? Explain
each factor.
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_________________ ......................................................................................................
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_________________ ......................................................................................................
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_________________ ......................................................................................................
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_________________ ......................................................................................................
Module P3: Forces for Transport
P3f: Crumple Zones
When cars stop energy is absorbed. This happens during braking and in collisions. Injuries in collisions can be reduced by clever
car design and this unit explores the science behind the safety features of modern vehicles. Collisions are studied here in terms
of energy, acceleration, force and momentum.
GRADE G - D
Use the equation:
GRADE C
Use the equation including a
change of subject:
GRADE B – A*
Use and apply the equation
including a change of subject:
momentum = mass × velocity
momentum = mass × velocity
to calculate momentum.
Describe why the greater the
mass of an object and/or the
greater the velocity, the more
momentum the object has in
the direction of motion.
Use the equation:
𝑓𝑜𝑟𝑐𝑒 =
𝑐ℎ𝑎𝑛𝑔𝑒 𝑖𝑛 𝑚𝑜𝑚𝑒𝑛𝑡𝑢𝑚
𝑡𝑖𝑚𝑒
to calculate force.
𝑓𝑜𝑟𝑐𝑒 =
𝑐ℎ𝑎𝑛𝑔𝑒 𝑖𝑛 𝑚𝑜𝑚𝑒𝑛𝑡𝑢𝑚
𝑡𝑖𝑚𝑒
Use Newton’s second law of
motion to explain the above
points:
F = ma
Targets for
Improvement
Recall that a sudden change in
momentum in a collision, results in
a large force that can cause
injury.
Explain how spreading the
change in momentum over a
longer time reduces the
likelihood of injury.
Explain, using the ideas about
momentum, the use of crumple
zones, seatbelts and airbags in
cars.
Describe the typical safety
features of modern cars that
require energy to be absorbed
when vehicles stop:
• heating in brakes, crumple
zones, seatbelts, airbags.
Describe how seatbelts, crumple
zones and airbags are useful in a
crash because they:
• change shape
• absorb energy
• reduce injuries.
Explain why seatbelts have to be
replaced after a crash.
Describe how test data may be
gathered and used to identify
and develop safety features for
cars.
Recognise the risks and benefits
arising from the use of seatbelts.
Recall and distinguish between
typical safety features of cars
which:
• are intended to prevent
accidents, or
• are intended to protect
occupants in the event of an
accident.
Explain why forces can be
reduced when stopping
(e.g. crumple zones, braking
distances, escape lanes, crash
barriers, seatbelts and airbags)
by:
• increasing stopping or collision
time
• increasing stopping or collision
distance
• decreasing acceleration.
Evaluate the effectiveness of
given safety features in terms of
saving lives and reducing injuries.
Describe how ABS brakes:
• make it possible to keep control
of the steering of a vehicle in
hazardous situations (e.g. when
braking hard or going into a skid)
• work by the brakes
automatically pumping on and
off to avoid skidding
• sometimes reduce braking
distances.
Analyse personal and social
choices in terms of risk and
benefits of wearing seatbelts.
P3f Activities
1. If two cars have the same mass but one is quicker than the other, which has the
most momentum?
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2. If both cars travel at the same velocity, but one is full with luggage and the other is
empty, which will have the most momentum?
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3. Complete the following calculations:
a) A snooker ball with a mass of 200 g moves with a velocity of 2 m/s. What is its
momentum?
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b) A car with a momentum of 50 000 kg m/s moves with a velocity of 20 m/s. What is
the mass of the car?
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c) A man with a mass of 70 kg walks with a momentum of 140 kg m/s. What is his
velocity?
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d) A car with a mass of 1000 kg accelerates from rest to a velocity of 15 m/s in 15 s.
What force is required to do this?
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e) If a force of 10 kN acts on a helicopter for 15 seconds, what is the change in
momentum?
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4. Two ice skaters at rest push off from each other. Jason has a mass of 60 kg and Jo
has a mass of 40 kg. If Jo moves away at +3 m/s then how fast does Jason move
away? (show all of your working out)
5.
(a) safety features intended to
prevent accidents
(b) safety features intended to
protect occupants in the event of
an accident
6. How does an air bag reduce the risk of injury?
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Module P3: Forces for Transport
P3g: Falling Safely
Falling objects are usually subject to at least two forces - weight and drag. Some cars have similar engines to others yet have very different
top speeds. This is to do with pairs of forces which may or may not balance. These ideas are of vital importance to the parachutist and
drag-racer who want to slow down in time - safely! Investigating falling whirligig, parachutes or plasticine shapes provides the opportunity
to explain phenomena by developing and using scientific theories. Work on the balance of forces illustrates the use of modelling in
developing scientific understanding.
GRADE G - D
Recognise that frictional forces (drag,
friction, air resistance):
• act against the movement
• lead to energy loss and inefficiency
• can be reduced (shape, lubricant).
Explain how objects falling through the
Earth’s atmosphere reach a terminal
speed.
Understand why falling objects do not
experience drag when there is no
atmosphere.
GRADE C
GRADE B – A*
Explain in terms of the
balance of forces how
moving objects:
• increase speed
• decrease speed
• maintain steady
speed.
Explain, in terms of balance of forces,
why objects reach a terminal speed:
• higher speed = more drag
• larger area = more drag
• weight (falling object) or driving
force (e.g. a car) = drag when
travelling at terminal speed.
Recognise that
acceleration due to
gravity (g) is the same
for any object at a
given point on the
Earth’s surface.
Understand that gravitational field
strength or acceleration due to
gravity:
• is unaffected by atmospheric
changes
• varies slightly at different points on
the Earth’s surface
• will be slightly different on the top of
a mountain or down a mineshaft.
Targets for Improvement
P3g Activities
1. Add force arrows and labels to each diagram below to show (i) increasing speed
(ii) decreasing speed (iii) steady speed:
(i) Increasing speed
(ii) Decreasing speed
(iii) Steady speed
2. Explain in terms of forces acting, why objects reach a terminal speed:
……………………………………………………………………………………………………………
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3. Tick whether the following statements are true or false:
Statement
Acceleration due to gravity is the same for any object at a given
point on the Earth’s surface.
Acceleration due to gravity is affected by atmospheric changes.
Acceleration due to gravity does not vary across the Earth’s
surface.
Acceleration due to gravity is less at the Equator than at the poles.
Acceleration due to gravity is 9.81 m/s2 but we often use 10 m/s2 for
calculations.
TRUE
FALSE
4. Label the graph for a skydiver below with as much detail as you can:
5. Describe a situation where drag is increased:
……………………………………………………………………………………………………………
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6. Describe a situation where drag is reduced:
……………………………………………………………………………………………………………
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7. What would happen if you dropped a hammer and a feather at the same time on:
(i) the Earth: …………………………………………………………………………………………...
……………………………………………………………………………………………………………
(ii) the Moon: ………………………………………………………………………………………...
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Module P3: Forces for Transport
P3h: Energy of Games and Theme Rides
Rides at theme parks are designed to thrill and frighten you in a safe way. We pay good money to have our ‘gravity’ distorted.
Theme ride designers are experts on energy and forces. Their simple trick is to use gravity and potential energy as the source of
movement. This item will help you understand the science of theme rides and how scientific understanding can be applied by
society.
GRADE G - D
Recognise that objects have
gravitational potential energy
(GPE) because of their mass
and position in Earth’s
gravitational field.
GRADE C
GRADE B – A*
Describe everyday examples
in which objects have
gravitational potential energy
(GPE).
Understand that for a body
falling through the atmosphere
at terminal speed:
• kinetic energy (KE) does not
increase
• gravitational potential
energy (GPE) is transferred to
increased internal or thermal
energy of the surrounding air
particles through the
mechanism of friction.
Use the equation:
GPE = mgh
Recognise and interpret
examples of energy transfer
between gravitational
potential energy (GPE) and
kinetic energy (KE).
Use and apply the equation,
including a change of subject:
GPE = mgh
Targets for
Improvement
Recognise everyday examples
in which objects use
gravitational potential energy
(GPE).
Interpret a gravity ride (rollercoaster) in terms of:
• kinetic energy (KE)
• gravitational potential
energy (GPE)
• energy transfer.
Describe the effect of
changing mass and speed on
kinetic energy (KE):
• doubling mass doubles KE
• doubling speed quadruples
KE.
Use and apply the relationship
𝑚𝑔ℎ =
1
𝑚𝑣 2
2
Show that for a given object
falling to Earth, this relationship
can be expressed as
h = v2 ÷ 2g
and give an example of how
this formula could be used.
P3h Activities
1. Give 3 examples of where objects have Gravitational Potential Energy (GPE):



2. When an object falls the kinetic energy gained is equal to the potential energy
lost:
KE gained = GPE lost
Substitute the equations from the formula sheet and rearrange to get an expression
for (i) v and (ii) h:
(i)
(ii)
3. Complete the following calculations:
a) The maximum number of people that a lift can safely take is 6 (each person is
assumed to have a mass of 80 kg). The mass of the lift is 300 kg. The lift goes up 10
floors, each 8 metres apart.
How much work will the lift’s motor have to do to lift a full safe mass up 10 floors?
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b) i) A car is driving along a mountain road. The combined mass of the car and the
luggage is 2920 kg. The car has a velocity of 23 m/s. How much kinetic energy does
the car have?
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(ii) At the top of the road, the car has gained a total height of 1200 m. Calculate the
potential energy the car has gained?
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(iii) As the car rounds a bend at the top of the mountain, a suitcase falls from the
roof into the valley below. The suitcase has a mass of 20 kg. Work out the potential
energy the suitcase lost when it had fallen a distance of 60 m.
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(iv)If all the potential energy of the suitcase is converted into kinetic energy, how fast
will it be travelling when it has fallen 60 m?
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(v) Explain why it will not actually be travelling as fast as this.
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4. If you double the mass, what effect will this have on the KE?
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5. If you double the speed, what effect will this have on the KE?
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P3 Equation Practice
Use the Equation sheet to complete the following questions:
1) 1m/s is an easy walking speed. How far would you cover in an
hour at this rate?
2) The braking distance is 35m for the car. If the stopping distance
is 50m, how far did the car travel before the driver put their foot on
the brakes?
3) A car is travelling at 40 m/s.
a) How far would it go in 1 minute? (Remember to turn this to
seconds.)
b) How long would it take to go 1000m?
4) Put the vehicles in order of acceleration.
5) When John pushes a lawnmower 20 m, he does 800 J of work.
What force did he apply?
6) The brakes in a car produce a force of 7000N and the car has
to lose 385000 J of kinetic energy. What is the braking distance?
7) A mother pushes a trolley with a force of 45N for a distance of
12m in 50s. What is her power output?
8) A car speeds up from 20 m/s to 35 m/s in 40s. What distance is
travelled?
These are six mark questions. You will also be assessed on the quality of
your written communication (spelling, punctuation and grammar).
The 6 mark question template
Science – write down
the key words/points you
will use:
(you can photocopy this page and use it to practice each of the questions)
Structure –
Write a brief plan of the
order you will write your
points :
1.
2.
3.
4.
5.
6.
6 marks? No
problem! Just
remember
SSS...
Now you are ready to
write your answer!
SPAG (spelling,
punctuation and
grammar).
Make sure you have
used full stops, commas,
and other punctuation
correctly.