1. P3

2. Speed How to calculate average speed
How speed cameras are used to measure speed
Calculate speed using a known time and distance

3. Calculating average speed
Average speed is calculated using this equation: d s x t
formula triangle
total distance
total time
average speed =
Speed can be measured in different units,
e.g. m/s, km/h, km/s, miles per hour.
The units of distance and time used will give the units to be used for speed.
How to calculate average speed
Distance, speed, time, units

4. d s x t Speed calculation example
A boy takes 1 hour to travel from his home to the cinema, a distance of 10 km. Calculate his average speed in km/h. d s x t
d (distance in km)
average speed
(in km/h)
t (time in h) =
10 km
1 h =
= 10 km/h
Cover the quantity to be
calculated - s (speed)
How to calculate average speed
Distance, speed, time, units

5. d s x t Speed calculation example – units check d (distance in m)
Sometimes the units have to be changed in a speed calculation. Here is the same problem but with different units:
A boy takes 1 hour to travel from his home to the cinema, a distance of 10 km. Calculate his average speed in m/s. d s x t
d (distance in m)
average speed
(in m/s)
t (time in s) =
3600 s
10,000 m =
1x60x60
= m/s
Cover the quantity to be
calculated - s (speed)
How to calculate average speed
Distance, speed, time, units

6. Question 1
A group set off from home and walk at an average speed of 3.6 km/h. How far would they travel in two hours?
Give your answer in km. d s x t
distance (km) = speed (km/h) x time (h)
= 3.6 km/h x 2 h
= 7.2 km

7. Distance – Time graphs How to draw and interpret distance-time graphs
That the gradient of a distance-time graph represents speed
Calculate the speed of an object from a graph

8. Which graph matches which description?
Libby
James:
Nasir
Karen
Mike

9. Distance
Time

10. That the gradient of a distance-time graph represents speed
Difference in distance
Difference in time
Gradient
(speed) =
That the gradient of a distance-time graph represents speed
Distance, speed, time, units

11. Acceleration and Velocity
How to calculate the acceleration of an object
The difference between speed and velocity
Calculate relative velocity

12. Recap Laura covers 2000m in 1,000 seconds. What is her speed?
How long would it take to run 100 metres if you run at 10m/s?
Steve travels at 50m/s for 20s. How far does he go?
S = D/T
= 2000m/1000s
= 2 m/s
T = D/S
= 100m/10m/s
= 10s
D = S x T
= 50m/s x 20s
= 1000m

13. This car is travelling at a speed of 20m/s
Speed vs. Velocity
Speed is simply how fast you are travelling…
This car is travelling at a speed of 20m/s
Velocity is “speed in a given direction”…
This car is travelling at a velocity of 20m/s east
The difference between speed and velocity
Speed, velocity, acceleration

14. T A Acceleration Acceleration = change in velocity (in m/s)
(in m/s2) time taken (in s)
E.g:
A Bugatti Veyron can do from 0 – m in 25.9 seconds
What is it’s acceleration?
Acceleration = m = 62.14m/s2
25.9 s
How to calculate the acceleration of an object
Speed, velocity, acceleration

15. Force and Motion the effects force can have on an object
How forces change the motion of objects
Use the equation force=mass x acceleration

16. Stopping Distances What a stopping distance is
The affects of stopping distance
Plot graphs to represent stopping distance

17. Stopping Distance Thinking Distance Braking Distance
The time needed for the driver to react to seeing something.
Thinking Distance
The total distance the car travels after the brakes have been applied
Braking Distance
The total distance needed to stop a car, including reaction time.
What a stopping distance is
Stopping, thinking, breaking distance

18. What a stopping distance is
What a stopping distance is
Stopping, thinking, breaking distance

19. Questions The affects of stopping distance
What factors can affect the thinking distance?
What factors can affect braking distance?
The factors that can affect thinking distance are; how tired you are, if you have used drugs or alcohol, distractions including music, sat navs or other passengers.
The factors that can affect braking distance are; the speed of the car, how good the brakes are and road conditions.
The affects of stopping distance
Stopping, thinking, breaking distance

20. Work and Power What the term ‘work done’ means
Work done is the same as energy transferred
Use equations to calculate work and power

21. Work Done = force x distance
(J) (N) (m)
Work is done when a force moves. People and machines do work.
When a person lifts a mass or pushes a shopping trolley work is done.
The more massive the object lifted or the heavier the shopping in a trolley, the more work is done because a larger force is being moved.
When the object or the trolley is moved a larger distance more work is done.
What the term ‘work done’ means
Work, power, watt, joules

22. Power Power = work done (J) (W) time (s)
Power is how quickly work is done. If a machine does a lot of work in a short space of time it has a high power.
It is measured in joules per second which scientists called watts (W).
A large amount of power is measured in kilowatts (kW). 1kW = 1000W
Use equations to calculate work and power
Work, power, watt, joules

23. Work Done = force x distance
(J) (N) (m)
Power = work done (J)
(W) time (s)
Use equations to calculate work and power
Work, power, watt, joules

24. Work Done = force x distance
(J) (N) (m)
Power = work done (J)
(W) time (s) W D F W T P
Use equations to calculate work and power
Work, power, watt, joules

25. Kinetic Energy and Fuelling Vehicles
The factors which affect kinetic energy
How electricity can be used to power vehicles
Discuss the advantges and disadveantages of electric vehicles

26. Kinetic energy = ½ x mass x speed2
Any moving object has energy due to its motion. This is its kinetic energy. Any moving object has kinetic energy. If an object is not moving, it has zero kinetic energy.
The size of an object’s kinetic energy depends on the mass of the object and the speed at which it is travelling.
Kinetic energy = ½ x mass x speed2
(joules, J) (Kilograms, kg) (metres per second, m/s)2
The factors which affect kinetic energy
Kinetic energy, fuel consumption, fossil fuel

27. Kinetic Energy Kinetic energy = ½ x mass x speed2
(joules, J) (Kilograms, kg) (metres per second, m/s)2
1) Find the kinetic energy of a car of mass 1200kg travelling at 20m/s.
Kinetic energy = ½ x 1200kg x (20m/s)2
= ½ x 1200 x 400
= J or 240kJ
The factors which affect kinetic energy
Kinetic energy, fuel consumption, fossil fuel

28. Fuelling Vehicles
Read pages 184 and 185 of your textbook and answer the following exam questions. (write the question and answer)
Explain what it means when we say that electric cars don’t produce pollution at their point of use. (2 marks)
State and explain 3 factors which affect fuel consumption of a typical car. (3 marks)
Outline the advantages and disadvantages of using electric cars over conventional fossil fuel powered cars. (6 marks QWC)
How electricity can be used to power vehicles
Kinetic energy, fuel consumption, fossil fuel

29. Extended writing question
Outline in detail two advantages and two disadvantages of using biofuels to generate electricity.
How will you structure your answer?
What is the question asking you?
What keywords should you include?
Describe the advantages and disadvantages of using fossil fuels and biomass
Biofuel, biomass, fossil fuel

30. Collisions and Car Safety
The safety features of cars
The effectiveness of safety features
Calculate momentum

31. Collapsible steering column
Safety Features
Paddle control
seatbelt
airbag
Crumple zone
Electric windows
Collapsible steering column
Traction control
ABS
The safety features of cars
Momentum, crumple zone, ABS

32. momentum = mass x velocity Force (N) = change in momentum (kg m/s)
During a collision a quantity called momentum is conserved. When the car slows down during impact its momentum decreases. As it decreases, the passengers feel a force which can result in injury, e.g. whiplash.
You can calculate momentum using this equation:
The force experienced by a passenger during a collision depends upon the rate of changes of momentum. The quicker the change in momentum, the greater the force experienced.
You can calculate the force using the following equation:
momentum = mass x velocity
Force (N) = change in momentum (kg m/s)
time taken (s)
The safety features of cars
Calculate momentum

33. 6 Mark Question
The safety features of cars
Calculate momentum

34. Falling objects and drag
How to calculate the weight of an object
The motion of an object falling under gravity
Explain that drag increases with speed

35. Terminal Speed
When a skydiver jumps out of an aeroplane, the speed of their descent can be considered in two separate parts:
Before the parachute opens (when the skydiver is in free-fall).
After the parachute opens (when air resistance is greatly increased).
The motion of an object falling under gravity
Weight, gravitational field strength, drag

37. Weight and Mass Weight is due to the force of gravity of an object.
The mass of an object is the amount of matter that it contains. Weight and mass are linked by two related formulae:
Weight (N) = Mass (kg) x Acceleration or free-fall (m/s²) or Gravitational field strength (N/kg)
How to calculate the weight of an object
Weight, gravitational field strength, drag

38. 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.

39. Gravitational potential energy
What factors affect GPE
The energy changes taking place as an object falls
Calculate GPE using an equation

40. The Conservation of Energy
Energy cannot be created or destroyed. It is converted into different forms.
For a roller coaster, energy is transformed between gravitational potential and kinetic energy.
The principle of conservation of energy tells us that gravitational potential energy (GPE) at the top of a roller coaster = kinetic energy (KE) at the bottom + energy transferred as heat and sound.

41. Gravitational Potential Energy
The gravitational potential energy (GPE) of an object is the energy stored due to:
its position in the Earth’s gravitational field (height)
its mass.
You can calculate GPE using this formula:
mass x gravitational field strength x vertical height
(kg) (N/kg) (m)

42. Fairground Rides
At the peaks on the ride the train has a lot of GPE (high up) and little KE (moves slowly).
In the middle of the ride GPE is decreasing and KE is increasing.
The more GPE gained by the train on the roller coaster, the greater it’s maximum speed.
At the bottom the train has little GPE (low down) but a lot of KE (moves fast).