Motion of vehicles

Question 1

what must happen in an emergency?

Answer 1

a driver must bring their vehicle to a stop in the shortest distance possible

Question 2

equation for stopping distance:

Answer 2

stopping distance = thinking distance + braking distance

Question 3

what is thinking distance?

Answer 3

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

Question 4

what is braking distance?

Answer 4

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

Question 5

factors that affect the driver’s reaction time? (4)

Answer 5

tiredness
drugs
alcohol
distractions

Question 6

how do longer reaction times affect the thinking distance?

Answer 6

Longer reaction times increase the thinking distance when stopping from a given speed.

Question 7

describe a way in which reaction time could be measured?

Answer 7

dropping a ruler between someone’s open thumb and forefinger

Question 8

factors that affect braking distance: (3)

Answer 8

-poor road and weather conditions
-poor vehicle conditions
-mass of the vehicle

Question 9

give an example of poor road conditions:

Answer 9

gravel, or wet or icy roads

Question 10

give an example of poor vehicle conditions:

Answer 10

worn brakes or worn tyres

Question 11

give an example of an increase in mass of the vehicle:

Answer 11

extra passengers

Question 12

how do poor road and weather conditions affect the braking distance?

Answer 12

less friction between tyres and the road

Question 13

how do poor vehicle conditions affect the braking distance?

Answer 13

less friction between brakes and wheels

Question 14

how does the mass of the vehicle affect the braking friction?

Answer 14

the braking friction has to work for a greater distance to remove the larger kinetic energy

Question 15

what happens when a force is applied to the brakes of a vehicle? and how does this effect the kinetic energy of the vehicle + other vehicle components?

Answer 15

-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 16

what is the correlation between the speed of the vehicle and the braking force?

Answer 16

The faster a vehicle travels, the greater the braking force needed to stop it in a certain distance will be

Question 17

what does a greater braking force produce?

Answer 17

A greater braking force produces a greater deceleration.

Question 18

why are large decelerations dangerous? (2)

Answer 18

• may cause the brakes to overheat,
  -the driver may also lose control of the vehicle.

Question 19

what is the thinking distance proportional to?
and why? (explain)

Answer 19

-thinking distance is proportional to the starting speed.

-because the reaction time is taken as a constant, and distance = speed × time.

Question 20

what does the braking distance increase by every time the starting speed doubles? and why?

Answer 20

-the braking distance increases four times each time the starting speed doubles.

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

Question 21

which type of energy is work?

Answer 21

Work done = kinetic energy

Question 22

considering that work is a force, how can it be implemented in an equation?

Answer 22

Work done = braking force × distance

Question 23

state the equation that links work and KE?

Answer 23

F x D = 1/2 x m x v^2

Question 24

if
stopping distance = thinking + braking distance
which equations could be used to deduce the stopping distance?

Answer 24

thinking distance:
D = S x T

braking distance:
D x F = 1/2 x M x V^2