Motion Of Vehicles

Question 1

What is a stopping distance!?

Answer 1

The sum of thinking distance and braking distance

The sum of thinking In an emergency, a driver must bring their vehicle to a stop in the shortest distance possible and braking distance.

Question 2

What is the thinking distance!?

Answer 2

The distance a vehicle travels in the time it takes for the driver to apply the brakes after realising they need to stop.

Question 3

What is the braking distance!?

Answer 3

The distance a vehicle travels in the time after the driver has applied the brake.

Question 4

What is the reaction time for a human!?

Answer 4

Reaction times vary from person to person, but are typically 0.2 s to 0.9 s.

Question 5

What can affect a driver’s reaction time!?

Answer 5

tiredness/fatigue
drugs
alcohol
distractions

Question 6

What do longer reaction times do!?

Answer 6

They increase the thinking distance when stopping from a given speed.

Question 7

How can the braking distance of a vehicle be increased!?

Answer 7

By poor road conditions
Poor vehicle conditions
More mass in the vehicle

Question 8

How do poor road and weather conditions affect the braking distance of a car!?

Answer 8

There is less friction between tyres and the road due to weather conditions such as gravel or wet and icy roads

Question 9

How does poor vehicle conditions affect the braking time of a vehicle!?

Answer 9

worn brakes or worn tyres can lead to - less friction between brakes and wheels

Question 10

How can more mass in the vehicle affect the braking distance of a vehicle!?

Answer 10

extra passengers for example) - the braking friction has to work for a greater distance to remove the larger kinetic energy

Question 11

When force is applied on the brakes what happens!?

Answer 11

there is work done by the friction between the brakes and the wheel. This reduces the kinetic energy of the vehicle, slowing it down and causing the temperature of the brakes to increase.

Question 12

What is work done!?

Answer 12

The amount of energy it takes to do a task. Measured in joules (J)

Question 13

What is friction!?

Answer 13

A force that opposes or prevents movement and converts kinetic energy into heat.

Question 14

Name an example of work done….

Answer 14

For example, the work done in raising a mass through 10 m would be equal to the gain in potential energy of the mass.

Question 15

What is kinetic energy!?

Answer 15

Energy which an object possesses by being in motion.

Question 16

What is deceleration!? And give an example

Answer 16

Slowing down or negative acceleration, eg the car slowed down with a deceleration of 2 ms⁻².

Question 17

The faster a vehicle travels…..

Answer 17

the greater the braking force needed to stop it in a certain distance. Resulting in a greater braking force

Question 18

What does a greater braking force produce!?

Answer 18

A greater braking force produces a greater deceleration. Large decelerations may cause the brakes to overheat, and the driver may also lose control of the vehicle.

Question 19

What is it important to be able to do when calculating stopping distances!?

Answer 19

estimate how the stopping distance for a vehicle varies with different speeds
calculate the work done in bringing a moving vehicle to rest

Question 20

What is important to note when creating a stopping distance graph!?

Answer 20

It is important to note that the thinking distance is proportional to the starting speed. This is because the reaction time is taken as a constant, and distance = speed × time.

Question 21

What happens to the braking distance when a starting speed doubles!?

Answer 21

It increase 4 times each time a starting speed doubles

Question 22

Why when the starting speed doubles does the braking distance increases 4 times!?

Answer 22

This is because the work done in bringing a car to rest means removing all of its kinetic energy.

Question 23

So for a fixed maximum braking force…….

Answer 23

….,.the braking distance is proportional to the square of the velocity