P3

Question 1

describe the relationship between thinking distance and speed

Answer 1

thinking distance is directly proportional to speed

Question 2

describe the relationship between stopping distance and speed

Answer 2

squared relationship (as speed doubles, stopping distance quadruples)

Question 3

state 2 factors that increase kinetic energy

Answer 3

• greater mass

- greater speed/velocity

Question 4

state 3 factors that affect fuel consumption

Answer 4

• amount of energy needed to increase kinetic energy of vehicle (depends on speed and mass of vehicle)
• work done against resistive forces e.g. air resistance, friction
• driving style
• road conditions

Question 5

state 3 car safety features

Answer 5

• crumple zones
• seat belts
• air bags

Question 6

explain how car safety features work in general to prevent/reduce injury

Answer 6

They cause the change in momentum to take place over a longer period of time, reducing the resultant force acting on the passenger.

Question 7

explain how data is gathered to design new safety features

Answer 7

• data is gathered from real crash sites and analysed

- data from crash test dummies is used to see the advantages and disadvantages of a safety feature

Question 8

explain how anti-lock braking (ABS) systems work

Answer 8

• they sense when the wheels are about to lock and reduce pressure on the brake pads, allowing the wheels to move for a short period of time
• they then reapply pressure
• they pump on and off like this until the car has stopped

Question 9

explain how the terminal speed can become slower, using the example of a skydiver opening a parachute

Answer 9

1. the skydiver is falling at a terminal speed
2. the skydiver opens his parachute
3. this increases drag (drag becomes larger than speed), so there is a resultant force upwards, and also an acceleration upwards
4. this causes the skydiver’s speed to decrease
5. as the skydivers speed decreases, so does drag (and therefore so does the resultant force upwards), until eventually, both are equal at a new, slower terminal speed, where there is no resultant force

Question 10

state 2 factors that will change GPE

Answer 10

• height (greater height, greater GPE)

- mass (greater mass, greater GPE)

Question 11

describe the relationship between speed and kinetic energy

Answer 11

squared relationship (as speed doubles, kinetic energy quadruples)

Question 12

describe the relationship between mass and kinetic energy

Answer 12

directly proportional (as mass doubles, kinetic energy doubles)