Stopping Distances (Edexcel GCSE Physics)

A car is travelling at 10 m/s.

The driver sees a danger and stops the car.

i) The stopping distance for the car would be smaller if the car

Figure 4 shows a speed-time graph for the driver stopping the car.

Figure 4

[1]

ii) Use the graph to find the driver’s reaction time.

reaction time = .............................................................. s[2]

Figure 5 shows the apparatus a student uses to investigate how the stopping distance of a toy car depends on the type of surface that it is stopping on.

Figure 5

Describe an experiment to find out how the stopping distance depends on the surface that stops the toy car.

Figure 6 shows a set of results used to find the average stopping distance of the toy car on a surface.

Figure 6

i) State the anomalous value of stopping distance given in the table in Figure 6.

[1]

ii) Use the results in Figure 6 to calculate the average stopping distance.

average stopping distance = ...................................... m[2]

iii) State one way the student could increase the speed of the car as it reaches the flat surface.

[1]

A car is travelling down a slope at 2.0 m/s.

The car accelerates for 4.0 s.

The speed of the car increases to 12 m/s. Calculate the acceleration of the car.

Use the equation

acceleration of the car = ......................... m/s²

Write down an equation which relates thinking distance, braking distance and stopping distance. 

A truck driver is travelling along a road at 25 m/s when they spot red traffic lights 200 m ahead.

The truck driver has a reaction time of 0.84 s, however they are tired so their reaction time is twice as long. 

Calculate the truck driver's thinking distance.

 Thinking distance = .................................... m

Figure 1 shows braking distances for average-weight trucks at different vehicle speeds in kilometres per hour (km/h).

Figure 1

25 m/s = 90 km/h. The lorry's brakes can produce a deceleration of 3.5 m/s².

Estimate the stopping distance of the lorry.

   Stopping distance = .................................... m

When the truck fully applies its brakes, it comes to rest only 5 m before the red light. 

Suggest two reasons why this may have happened.

State two factors that can affect reaction distance.

State two factors that affect the braking distance

A council introduces 20 miles per hour (mph) speed limit in a particular region of a city.

A member of the council states that drivers can react faster at 20 mph than they can at 30 mph.

Explain what is wrong with the councillor's statement.

Figure 1 shows thinking and braking distances for a vehicle at different speeds.

Figure 1

Describe how thinking distance varies with increasing speed.

Use data from the graph in your answer.

Complete the equations. Choose quantities from the box. 

Each quantity can be used once, more than once or not at all.

During a braking test, 900 kg car is travelling at 40 m/s.

The test driver must brake sharply and come to a complete stop when she sees a light flash at the end of the road.

Calculate the work done by the brakes to bring the car to a stop.

  Work done = .................................... J

A car brake manufacturer states that their brakes can produce a maximum braking force of 6250 N.

Calculate the braking distance of the car from part (b) if the car is using these brakes.

  Braking distance = .................................... m

In reality, after the light flashes the car travels further than the value calculated in (c). 

Explain why this happens.

A scientist uses different drivers to test the stopping distances of the same car.

Figure 1 shows the results.

  Figure 1

Most of the drivers tested the car on a dry day, on a level road.

State which driver tested the car on a wet road.

State which driver has the shortest reaction time.

Calculate their reaction time, giving your answer to 1 significant figure.

The car has a mass of 1400kg.

(i) Calculate the maximum energy in the car's kinetic store when driver 4 is testing it.

[3]

(ii) Describe what happens to the energy in the car's kinetic store as it brakes and stops.

[2]

(iii) The braking distance of the car is 82 m.  

Calculate the braking force on the car to 2 significant figures.   

[3]

Driver 2 travels at 24 m/s on the road. The thinking distance is 20m and the braking distance is 36 m.

Calculate the deceleration of the car.

You may assume the braking force is uniformly applied.