Starter quiz
- Which force is caused by two solid surfaces moving across each other?
- drag
- electromagnetic
- friction ✓
- gravitational
- upthrust
-
- When a vehicle increases its speed, it is accelerating and when it decreases its speed, it is ...
- 'decelerating' ✓
The figure shows a dynamics trolley just after it has reached the end of a ramp. Which of the following statements help explain why the trolley slows down when it has left the ramp?- The size of the forward force is increasing.
- There is no forward force acting on the trolley. ✓
- A drag force pushes the trolley forwards.
- A frictional force acts in the direction opposite to the movement. ✓
- A drag force acts in the direction opposite to the movement. ✓
-
- Which of the following is the correct equation for calculating the kinetic energy of an object?
- kinetic energy = mass × speed
- kinetic energy = ½ × mass × speed
- kinetic energy = ½ × (mass) × speed
- kinetic energy = ½ × mass × (speed) ✓
- kinetic energy = ½ × (mass) × (speed)
-
- A motorcycle is travelling at 9.00 m/s. How far will the motorcycle travel in 1.40 s?
- 0.15 m
- 6.43 m
- 7.60 m
- 10.4 m
- 12.6 m ✓
-
- A motorcycle has a mass of 200 kg and is travelling at 9.00 m/s. Calculate the kinetic energy of the motorcycle. Give the unit.
- '8100 J' ✓
Exit quiz
- Match the following key terms to their definitions.
- reaction time⇔time between noticing a hazard and taking an action to deal with it ✓
- thinking distance⇔distance a vehicle travels during the time a driver takes to react ✓
- braking distance⇔distance a vehicle travels before stopping after brakes are pressed ✓
- stopping distance⇔sum of the thinking and braking distances ✓
- Where is most of the energy from the kinetic store transferred to when a vehicle brakes and slows down?
- to the chemical store, increasing the amount of fuel
- to the thermal store, heating the brakes ✓
- to the thermal store, heating the engine
- to the gravitational store, raising the vehicle up a hill
-
- Which of the following factors affect both the thinking distance and the braking distance of a vehicle?
- wet roads
- worn tyres
- alcohol consumption
- vehicle speed ✓
- caffeine consumption
-
- A driver with a reaction time of 1.2 s is travelling at 30 m/s along a road. Calculate the thinking distance for this driver. Give the correct unit.
- '36 m' ✓
- The driver of a lorry travelling at 12.0 m/s notices a hazard. The driver's reaction time is 0.80 s and, at this speed, the braking distance of the lorry is 25.0 m. Calculate the stopping distance.
- 13.0 m
- 29.6 m
- 34.6 m ✓
-
- A car is travelling at 30 m/s and, at this speed, its braking distance is 75 m. Calculate the minimum reaction time needed to stop the car in less than 90 m. Give the correct unit.
- '0.5 s' ✓
Worksheet
Loading worksheet ...
Presentation
Loading presentation ...
Video
Lesson Details
Key learning points
- Stopping distance is the distance travelled both as a drive reacts and then for the brakes to bring a vehicle to a stop
- Reaction time of a drive can be affected by tiredness, drugs, alcohol or distractions
- Braking distance can be affected by adverse road and weather conditions and the condition of the vehicle
- When braking, work is done on the brakes that heats them up
- If brakes overheat they can stop working effectively and lead to a loss of control
Common misconception
Pupils often forget to include thinking distance in the overall stopping distance, or imagine that thinking distance is too short to matter.
Model a situation in which a child steps out from behind a parked car 10 m in front of a driver. At 20 mph the thinking distance is about 6 m and braking distance 6 m; at 30 mph these are 9 m and 14 m.
Keywords
Reaction time - for driving is the time between noticing a hazard and taking an action to deal with it
Thinking distance - is the distance a vehicle travels while a driver reacts; the vehicle does not slow during this time
Braking distance - is the distance a vehicle travels between the brakes being applied and the vehicle coming to a stop
Stopping distance - is the sum of the thinking and braking distances
+