Practice Question

1.Define the term braking distance

Braking distance is the distance travelled whilst a braking force is being applied to the vehicle. 

2. State 3 factors that affect braking distance and explain how they affect its value. 

1. Speed of the vehicle, faster the vehicle, the greater the braking distance

2. Poor brakes or tyres on the vehicle will reduce friction, which increases braking distance

3. Adverse road conditions such as wet or icy roads will reduce friction, increasing braking distance. 

3. Describe the energy transfer that occurs when a vehicle’s brakes are applied.

As the brakes are applied the kinetic energy store of the car is converted mechanically into the thermal energy store of the brakes.

4. How does the speed of a vehicle affect the braking force required to stop it within a certain distance?

As speed of the vehicle increases, so does the braking force needed to stop the vehicle within a certain distance. This is because if the vehicle is travelling faster, it has more kinetic energy, so more work (energy transferred) has to be done to cause the vehicle to decelerate, so a larger braking force is needed to stop the vehicle. 

5.What are the potential dangers associated with large decelerations during braking?

Large braking force can cause overheating of the brakes or loss of control of the vehicle.

6.If a car has a mass of 1,000 kg and is traveling at 20 m/s, calculate its braking force if the braking distance is 50m.