FM1 - Stopping distance and momentum + collision Flashcards Preview

IGCSE - Physics > FM1 - Stopping distance and momentum + collision > Flashcards

Flashcards in FM1 - Stopping distance and momentum + collision Deck (21):
1

What is the stopping distance of a car?

The distance covered in the time between the driver first spotting a hazard and the car coming to a complete stop

2

What is the distance it takes to stop divided into?

The thinking and braking distance

3

What is the thinking distance of a car?

The distance the car travels between the driver noticing the hazard and applying the breaks

4

What two factors affect the thinking distance?

1) How fast you're going
2) How tired you are - tiredness, drugs, alcohol and old age can affect your reaction time

5

What is the braking distance?

The distance the car travels during deceleration whilst the breaks are being applied

6

What four factors affect the breaking distance?

1) How fast your going - the faster your going, the further it takes to stop
2) The mass of the vehicle - the larger the mass, the longer it takes to stop
3) How good your brakes are - should be checked regularly
4) How good the grip is - depends on road surface, weather conditions and tyres "aquaplaning"

7

How can bad visibility be a major factor for incidents?

Lashing rain, thick fog and bright upcoming lights might mean that the driver doesn't notice a hazard until they're quite close having a shorter distance available to stop in

8

What is momentum?

A vector quantity

9

What is the equation for momentum?

Momentum (kg m/s) = Mass(kg) x Velocity(m/s)

10

The greater the mass of the object, the greater the velocity...

The more momentum

11

What does momentum before equal?

Momentum after

12

Why does momentum before = momentum after?

Momentum is conserved when no external forces act f

13

When working out momentum questions what should you always label the directions with?

Positive and negative

14

What do forces cause?

Changes in momentum

15

A large force means...

A faster change in momentum (greater acceleration)

16

What is the equation linking force, momentum and time?

Force (N) = Change in momentum(kg m/s) /time taken(s)

17

Give an example of when momentum changes very quickly

In a car crash - the forces on the body are very large and are more likely to cause injury

18

Why are cars designed to slow people down over a longer time when they crash?

The longer it takes for a change in momentum, the smaller the force and so the less serve the injuries will be

19

How does a crumple zone in a car slow down momentum?

Increases time taken for the car to stop

20

How do seat belts in a car slow down momentum?

They stretch slightly increasing the time taken for the wearer to stop. This reduces the forces acting on the chest h

21

How do air bags in a car slow down momentum?

Slow you down gradually