Duncanrig Secondary School
East Kilbride
S3 Physics Elective
Transport
Pupil Booklet
Name:
Class:
Aspects of the following outcomes in bold are covered by this topic of work.
SCN 4-07a – I can use appropriate methods to measure, calculate and display graphically the
speed of an object, and show how these methods can be used in a selected application.
SCN 4-07b – By making accurate measurements of speeds and acceleration, I can relate the
motion of an object to the forces acting on it and apply this knowledge to transport safety.
 Learning Outcomes
 Homework Exercises
 Unit Summary
S3 Physics Elective
Transport
Working at Home
TO THE PUPIL
Each day you have Physics at school, you should set aside time for work at
home. By this stage you should be accepting more responsibility for your own
learning and should undertake the following tasks on a regular basis:
 Tackle the supplied homework sheets as each section of work is
completed in class. Ensure you meet the deadlines issued by your
teacher.
 Check your own progress in the homework sheets by referring to the
homework answer files available in class. Discuss any difficulties that
arise with your class teacher.
 Complete any informal homework tasks that your teacher may issue from
time to time and hand them in on the due date for marking.
 Revise the work you have covered in class activities by referring to your
class work jotter and unit summary. Referring to the learning outcomes
can also help.
 Make your own short notes to cover each learning outcome in the
supplied study guides.
 It is your responsibility to catch up on missed work. Use the learning
outcomes and summary to help you do this. Speak to your classmates
and ask your teacher.
Page 1
S3 Physics Elective
Transport
Working at Home
Homework – Getting Started
Success involves doing many kinds of problems which help improve your knowledge
and understanding of the content of the course and your ability to solve problems.
To get started we will look at a general method for tackling problems.
General Method for Solving Problems.
Any numerical problem in Physics can be solved using the following steps:
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Read the question carefully.
Find out exactly what is being asked.
Extract the key data.
Select the correct equation.
Substitute the data into the equation and find the missing variable.
Give the answer and correct unit.
Example
How far does a cyclist travel in 26 seconds if she is travelling at a constant
speed of 8 metres per second?
Solution
Read the question carefully
Find out exactly what is being asked
Distance (how far)
Extract the key data
time = 26 seconds
speed = 8 metres per second
Select the correct equation
Substitute data into equation
Give the answer and correct unit
distance = speed x time
d = 8 x 26
d = 208 m
Page 2
S3 Physics Elective
Transport
Working at Home
Usual Layout
d=?
v = 8 m/s
t = 26 s
d=vxt
= 8 x 26
= 208 m
All numerical questions in the following homework exercises should be carried
out in this way. No marks will be awarded for an answer given without the
working being shown.
Helpful Hint
Always watch the units in an equation. They may need to be
converted before being put into an equation.
e.g. 3 ms = 0.003 s
= 3 x 10-3 s
6 km = 6000 m = 6 x 103 m
Page 3
S3 Physics Elective
Transport
FORMULAE FOR THIS UNIT
d = vt
instantaneous speed = length of mask / time beam is broken
thinking distance = speed x reaction time
stopping distance = thinking distance + braking distance
a = (v – u) / t
OR
v = u + at
Page 4
Working at Home
S3 Physics Elective
Transport
Learning Outcomes
How Confident am I with the Learning Outcomes?
 Circle the faces to keep a record of your progress.
 I am confident that I understand this and I can apply this to
problems
 I have some understanding but I need to revise this some more
 I don’t know this or I need help because I don’t understand it
 You can use this to help you pick the areas of the unit that need the
most revision.
 As you revise your class work you will be able to circle more and more
smiley faces.
 If that does not help then you should ask your teacher!
Learning Outcomes
1.
2.
3.
4.
5.
6.
Can you do
this?
State that speed is the distance
covered per unit of time.
Use the formula d = vt to calculate
average speed.
Describe how to measure average speed.
Describe a road safety application where
average speed is calculated.
State that the stopping distance for a
vehicle is the sum of the thinking
distance and braking distance.
State that thinking distance is the
distance covered by a vehicle while the
brain is processing (before the brakes
are applied).
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Comments
S3 Physics Elective
Transport
7. Use the formula d = vt to calculate the
thinking distance (where v is the speed
of the vehicle and t is the
thinking/reaction time)
8. Know various factors that can affect
reaction (thinking) times.
9. State that the braking distance is the
distance covered by a vehicle while
coming to a stop (after the brakes are
applied)
10. Know various factors that affect the
braking distance.
11. Use the formula d = vt to calculate
instantaneous speed (where v is the
instantaneous speed, d is the length of
the mask, and t is the time the beam is
broken)
12. Describe how to measure instantaneous
speed.
13. Know the difference between average
speed and instantaneous speed.
14. Describe a road safety application where
instantaneous speed is calculated.
15. State that the definition for
acceleration is the change in speed per
second measured in metres per second
per second (m/s2).
16. Use a = (v-u)/t OR v = u + at in
acceleration and deceleration
calculations.
17. Describe a method for measuring
acceleration experimentally.
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Learning Outcomes
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S3 Physics Elective
Transport
18. Convert quantities to appropriate units
prior to using formula.
19. Describe a road safety application where
acceleration is calculated.
20. State that if the time of impact of a
collision is longer the deceleration is
less.
21. Crumple zones can increase the time of
impact in a crash and absorb the energy
from the impact.
Page 7
Learning Outcomes
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Answer the questions in this homework, where appropriate in full sentences, on the blank page that follows.
Transport Homework 1 – Average Speed and Cameras
1. Jane jogs to work every day at an average speed of 4 m/s. Most days it
takes her 600 s to reach work. Calculate how far she jogs.
(2)
2. A top class sprinter covers the 100 m in a time of 10 s. Calculate the
sprinter's average speed.
(2)
3. How long will it take a Formula 1 car to travel one lap around a 5 km long
circuit if it is travelling at an average speed of 180 km/h?
(2)
4. In a school experiment, a small trolley is allowed to run down a ramp.
(a) Describe how the average speed of the trolley could be measured.
(b) During one run the trolley is found to take 2.5 s to travel between
the lines which are 0.8 m apart. Find the average speed of the
trolley.
5. An average speed camera on the M77 records a vehicle passing an
entrance camera at 12.05 pm. When the number plate is digitally
recorded leaving the exit camera the time is 12.07 pm. Show whether
the vehicle was speeding if the distance between the entrance camera
and exit camera was 4 km and the speed limit on the road was 60 m.p.h.
(3)
(2)
(3)
(Note: to convert from m/s to m.p.h. multiply by 2.24)
Total 14 marks
Page 8
Complete Homework 1 – Average Speed and Cameras below.
Page 9
Answer the questions in this homework, where appropriate in full sentences, on the blank page that follows.
Transport Homework 2 – Reaction Times and Stopping Distances
1.
Use the diagram below to answer questions (a) and (b).
(a) You are travelling at 30 m.p.h. in good road conditions when you
suddenly see children crossing the road, what would be the overall
stopping distance for your car?
(b) What happens to the stopping distances when the speed of the car
increases?
(c) What is meant by the term thinking distance?
(d) What would happen to your thinking distance if you were driving when
tired? Why would this happen?
(e) If your car is going faster will your reaction time alter? Explain your
answer.
2.
(1)
(1)
(1)
(2)
(2)
Calculate the thinking distance for the data in the table below.
Thinking/Reaction Time (ms)
Speed of vehicle (m/s)
2000
20
750
25
650
30
(Note: to convert from ms to s divide by 1000)
(6)
Total 13 marks
Page 10
Complete Homework 2 - Reaction Time and Stopping Distances below.
Page 11
Answer the questions in this homework, where appropriate in full sentences, on the blank page that follows.
Transport Homework 3 – Instantaneous Speed and Cameras
1.
A bike is travelling along a cycle track.
(a)
Describe how you could measure the instantaneous speed of the bike. (3)
(b)
If the bike took 0.5 s to pass a horizontal line of the track and the length
of the bike was 2 m, calculate the instantaneous speed of the bike.
2.
(2)
A coin is dropped from a height so that it passes through a light gate
connected to a computer. The coin has a width of 0.02 m and it takes 0.05 s
to pass through the light gate. Find its instantaneous speed.
3.
(2)
What is the name of the device on a vehicle that displays the instantaneous
speed?
4.
(1)
A driver receives a speeding fine as when he drove through a speed trap he
covered 7.62 m in 0.3 s.
(a)
Calculate his speed in m/s.
(2)
(b)
Convert his speed to m.p.h. (multiply by 2.24).
(1)
(c)
Suggest a possible speed limit for the road he was driving.
(1)
Total 12 marks
Page 12
Complete Homework 3 - Instantaneous Speed and Cameras below.
Page 13
Answer the questions in this homework, where appropriate in full sentences, on the blank page that follows.
Transport Homework 4 – Acceleration
1.
What is the definition of acceleration?
(1)
2.
The table below shows the performance figures for some makes of car.
Which row in the table shows the car that will go from 0 – 60 m.p.h in the
shortest time?
(1)
Car
Top speed
(mph)
Acceleration
(mph per second)
A
B
C
D
109
105
107
119
4.95
5.32
5.45
4.50
3.
Calculate the acceleration of a car that increases its speed by 10 m/s in 5 s.
(2)
4.
Calculate the final speed of a train which accelerates uniformly at a rate of
0.6 m/s2 from a speed of 2 m/s for 30 s.
(2)
5.
A motorbike can accelerate from 10 m/s to 26 m/s in 8 s. Calculate its
acceleration.
(2)
6.
Calculate the deceleration of a car with initial velocity 30 m/s which comes to
rest in 15 s.
(2)
7.
Use the values from the speed/time graph below to calculate the acceleration
of the vehicle.
(2)
Speed/Time Graph
60
Speed (m/s)
50
40
30
20
10
0
0
2
4
6
Time (s)
Page 14
8
10
12
Total 12 marks
Complete Homework 4 - Acceleration below.
Page 15
Answer the questions in this homework, where appropriate in full sentences, on the blank page that follows.
Transport Homework 5 – Test Preparation
1.
If you have not already done so work your way through the learning outcomes,
at the front of this booklet, circling the appropriate face. Make sure you are
referring to your jotter and summary notes as you work your way through
each one. Speak to your classmates and teacher to help you with weaker
areas.
2.
Revise the unit summary. It may be helpful to draw a mind map, highlight the
notes, or write your own. It is important that you do more than just reading.
3.
For each section in the summary design a question that could be asked in the
exam. Write down your question and answer in the following form.
e.g.
4.
Section
Reaction Times and Stopping Distances
Question Name a factor that affects human reaction time.
Answer
Alcohol levels.
Practise your numerical work by answering the following questions.
(a)
A toy car covers a distance of 0.6 m in a time of 2 s. Calculate the
average speed of the car.
(2)
(b)
A football of diameter 20 cm cuts a light beam for 0.25 s. Calculate the
instantaneous speed of the ball.
(2)
(c)
Calculate the thinking distance if the driver’s reaction time is 0.7 s and
he is travelling at a speed of 20 m/s.
(2)
(d)
A motorcycle accelerates constantly from 20 m/s to 35 m/s in a time of
3 s. Calculate the acceleration of the motorbike.
(2)
(e)
Calculate the final speed of a car if it accelerates at 4 m/s2 for 5 s. Its
initial speed was 10 m/s.
(2)
(f)
A lorry driver brakes and decelerates at a constant rate from 12 m/s to
4 m/s in a time of 4 s. Calculate the deceleration.
(2)
Page 16
Complete Homework 5 - Test Preparation below (if appropriate).
Page 17
The unit summary is provided to help supplement your class notes and should be used when completing homework
and studying for the test. Along with the learning outcomes, it can be used to help you catch up on missed work.
Unit Summary
Section 1 – Average Speed
Speed Definition
The speed of an object is a measure of the distance covered in a unit of
time, for example a speed of 50 m/s means that the object travels 50 m each
second or 60 km/h means the object travels 60 km every hour.
Calculating Average Speed
Average speed is a measurement of speed that takes into account that the object
may have accelerated, decelerated, travelled at different constant speeds, and
could even have stopped during the journey. Therefore, it is an average for the
whole journey.
We can calculate the average speed of an object using the formula d = vt
where: d represents distance
v represents the average speed
t represents time
Using the Correct Units for Speed Calculations
It is important to consider your units when calculating speeds.
The units you use for speed can be determined from your units for distance and
time.
Page 18
The unit summary is provided to help supplement your class notes and should be used when completing homework
and studying for the test. Along with the learning outcomes, it can be used to help you catch up on missed work.
If d is measured in
metres
kilometres
miles
(m)
(km)
(M or m.)
seconds
hours
hours
(s)
(h)
(H or h)
metres per
kilometres per hour
miles per hour
second
(km/h)
(MPH or m.p.h.)
and time is measured in
then the speed is measured in
(m/s)
Sometimes there is the need to convert from one unit to another.
e.g.
3 ms
=
0.003 s
=
3 x 10-3 s
6 km
=
6000 m
=
6 x 103 m
Using d = vt to Calculate Average Speed
This is how to calculate the average speed if the vehicle took 30s to travel 150m.
d = 150 m
v=?
t = 30 s
d=vxt
150= v x 30
v = 150 / 30
= 50 m/s
Describing a Method for Measuring Average Speed
Measure the distance the object travelled using a tape measure. Measure the
time taken to travel that distance using a stopwatch. Use the formula d = vt to
calculate the average speed.
Page 19
The unit summary is provided to help supplement your class notes and should be used when completing homework
and studying for the test. Along with the learning outcomes, it can be used to help you catch up on missed work.
Average Speed Cameras
Some roads have average speed cameras along their length.
As vehicles pass
between the entry and exit camera points their number plates are digitally
recorded, whether speeding or not. Then, by Automatic Number Plate Recognition
(ANPR), the images on the video of matching number plates are paired up, and
because each image carries a date and time stamp, the computer can then work
out the average speed between the cameras using the formula d = vt.
Section 2 - Reaction Time and Stopping Distances
Reaction Time and Stopping Distances
When a vehicle stops there are two factors that contribute to the stopping
distance:
1.
The thinking distance which is the distance covered by the moving vehicle
while the driver’s brain is processing that he needs to stop (before the
brakes are applied).
2.
The braking distance which is the distance covered once the brakes are
applied.
Stopping distance = thinking distance + braking distance.
The thinking distance can be calculated from the formula d = vt, where v is the
speed of the vehicle and t is the thinking time (or reaction time). This means that
if the speed and/or reaction time increases, so does the thinking distance.
Page 20
The unit summary is provided to help supplement your class notes and should be used when completing homework
and studying for the test. Along with the learning outcomes, it can be used to help you catch up on missed work.
Reaction times increase if a driver has been drinking, taking drugs, and/or is
tired. In addition, if the driver is distracted by using a mobile phone or changing
music this will also increase their reaction time.
The diagram below shows typical stopping distance at speeds from 20m.p.h. to
70m.p.h. illustrating that an increase in speed increases the thinking, braking, and
overall stopping distances.
If the roads are wet or icy braking distances increase.
The Venn diagram below shows how various factors can affect thinking and
braking distances.
Page 21
The unit summary is provided to help supplement your class notes and should be used when completing homework
and studying for the test. Along with the learning outcomes, it can be used to help you catch up on missed work.
Section 3 - Instantaneous Speed
Instantaneous Speed
The instantaneous speed is the speed of the vehicle at that instant.
speedometer on a car displays the instantaneous speed.
The
To calculate
instantaneous speed the time recorded must be very short; this can be done by
making the distance very short, for example, the length of the vehicle or
something on the vehicle (a card/mask). Since the time measured is very short
human reaction time can adversely affect this value of time.
To stop human
reaction time affecting time measurements a light gate connected to a computer
(set to be a timer) can be used. In this situation the d = vt equation becomes:
instantaneous speed = length of mask / time beam is broken
Using d = vt to Calculate Instantaneous Speed
This is how to calculate the instantaneous speed of a vehicle of length 4m that
took 0.5s to pass a horizontal line on the road.
d=4m
v=?
t = 0.5 s
d=vxt
4= v x 0.5
v = 4 / 0.5
= 8 m/s
Describing a Method for Measuring Instantaneous Speed
Measure the length of the object (or mask on the object) using a ruler. Allow the
object to cut the beam of a light gate and record the time the beam is broken
from the timer. Use the formula d = vt to calculate instantaneous speed where d
is the length of the object and t is the time the beam is broken for.
Page 22
The unit summary is provided to help supplement your class notes and should be used when completing homework
and studying for the test. Along with the learning outcomes, it can be used to help you catch up on missed work.
Instantaneous Speed Cameras
There are many types of instantaneous speed cameras designed to
monitor that drivers are observing the speed limit.
The Gatso
speed camera projects a radar beam onto your vehicle which
tracks your speed. If it senses you're driving above the limit then
it takes 2 photos, the second photo is taken a fraction of a second after the
first. Drivers are warned that they are approaching a speed camera by the speed
camera sign. They will also see white lines on the road, this indicates the have
entered the speed trap area.
These white line markings on the road surface
provide a secondary method of calculating the drivers speed using d = vt, where d
= the distance between the markings and t = the time to cover that distance.
Section 4 - Acceleration
Definition of Acceleration
Acceleration is the change in speed per unit of time. If the speed is measured in
m/s and the time in s then the units for acceleration are m/s2.
Acceleration Formula
Acceleration can be calculated from the formula
a=v–u/t
where: a represents acceleration
v represents the final speed
u represents the initial speed
t represents time
Page 23
The unit summary is provided to help supplement your class notes and should be used when completing homework
and studying for the test. Along with the learning outcomes, it can be used to help you catch up on missed work.
However, it can be easier to work with this formula in the form v = u + at if you
have been asked to calculate v, u, or t.
Using a = v – u / t to Calculate Acceleration
This is how to calculate the acceleration of an object initially at rest whose speed
increases to 20 m/s in 4 s.
a=?
u = 0 m/s
v = 20 m/s
t=4s
a=v–u/t
= 20 – 0 / 4
= 20 / 4
= 5 m/s2
Using v = u + at to Calculate Final Speed
This is how to calculate the final speed of an object accelerating at 2 m/s2 from
10 m/s in a time of 8 s.
a = 2 m/s2
u = 10 m/s
v=?
t=8s
v = u + at
= 10 + 2(8)
= 26 m/s
Calculating Acceleration from a Speed/Time Graph
Sometimes the information needed to calculate acceleration can be presented on
a=v–u/t
= 50 – 0 / 5
= 50 / 5
= 10 m/s2
60
50
40
30
(m/s)
a=?
u = 0 m/s
v = 50 m/s
t=5s
Speed (m/s)
a graph.
20
10
0
0
1
2
3
Time (s)
Page 24
4
5
6
The unit summary is provided to help supplement your class notes and should be used when completing homework
and studying for the test. Along with the learning outcomes, it can be used to help you catch up on missed work.
Deceleration
A negative acceleration is referred to as deceleration and can be calculated from
the formula a = v – u / t.
Using a = v – u / t to Calculate Deceleration
This is how to calculate the deceleration of a vehicle travelling at 15 m/s which
slows to 5 m/s in a time of 4 s.
a=?
u = 15 m/s
v = 5 m/s
t=4s
a=v-u/t
= 5 – 15 / 4
= -10 / 4
= -2.5 m/s2
A Method to Measure Acceleration Experimentally
The following experimental set up can be used to measure the acceleration of a
trolley running down a slope. Set the computers to measure speed. Input the
length of the mask. As the mask on the trolley cuts the first light gate, then the
second, the computers calculate the initial and final speeds using
instantaneous speed = length of mask / time beam is broken.
The stop clock is used to time how long it takes the trolley to run from the first
to second light gate.
The formula a = v – u / t is used to calculate the
acceleration.
Computer
Mask
on
trolley
Computer
Slope
Light
gate
Stop clock
Page 25
The unit summary is provided to help supplement your class notes and should be used when completing homework
and studying for the test. Along with the learning outcomes, it can be used to help you catch up on missed work.
Section 5 – Crumple Zones
Crumple Zones
Crumple zones on cars are designed to absorb the impact of a crash so as to
protect the occupants inside.
They also make the time of impact of a crash
longer as this reduces the deceleration. Crumple zones can be on the front, back
and even the sides of vehicles. Euro NCAP organizes crash-tests to assess the
safety of some of the most popular cars sold in Europe.
One of the tests they carry out is on crumple zones to
see how effective they are at protecting the occupants.
The crumple zone is sacrificed in a car crash in order to
keep the passenger compartment intact.
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