Stopping Distances Practice Questions

Which of these is a typical value for a person's reaction time?

Put a cross ( ☒ ) in the box next to your answer.

☐ A $0.02\ \text{s}$

☐ B $0.25\ \text{s}$

☐ C $2.5\ \text{s}$

☐ D $25\ \text{s}$

Describe how the ruler drop test is carried out to measure a person's reaction time.

A driver has a reaction time of $0.6\ \text{s}$.

The driver is driving at a speed of $13\ \text{m/s}$ when a dog runs into the road.

Calculate the thinking distance of the driver.

thinking distance = .............................................. m

Complete the table.

Calculate the reaction time of the driver of this car.

Explain how the braking distance of this car depends on its speed.

The brake pads on this car become badly worn.

State and explain the effect this has on the thinking distance and on the braking distance at $20\ \text{m/s}$.

Describe how a computer-based test can be used to measure a driver's reaction time.

State two factors that increase a driver's reaction time.

Two drivers in identical cars are driving at the same speed on the same dry road. One of the drivers has been drinking alcohol.

Explain why the stopping distance of the car driven by the driver who has been drinking alcohol is greater.

Calculate the deceleration of the car.

Use the equation

$$v^2 - u^2 = 2 \times a \times x$$

deceleration = .............................................. m/s$^2$

Later the same day it rains. The driver brakes from $20\ \text{m/s}$ on the same road and the braking distance is now $40\ \text{m}$.

Explain why the braking distance is greater on the wet road.

The driver then loads the car with four passengers and heavy luggage, so the mass of the car is much greater.

The driver brakes from $20\ \text{m/s}$ on the same dry road.

State and explain the effect of the extra mass on the braking distance.

Calculate the deceleration of the car.

deceleration = .............................................. m/s$^2$

Estimate the force acting on the passenger as the car stops.

force = .............................................. N

Explain why large decelerations are dangerous for the people inside a vehicle.

Use your answer to part (b) in your explanation. The weight of the passenger is about $600\ \text{N}$.

Evaluate the driver's statement.

In your answer you should use the data in the table and your knowledge of the factors that affect thinking distance and braking distance, including the effect of wet weather.