Moments + Momentum (including Safety Features)

Question 1

How does protective equipment reduce the risk of injury to the player (5)

Answer 1

• there is a change of momentum (when ball hits player)
• (equipment) increases (impact) time
• decreases rate of change of momentum (of ball)
• decreases force (on player)
• decreases pressure (on player)

Question 2

Principle of conservation of momentum

Answer 2

Total P before = Total P after

Question 3

Principle of moments

Answer 3

• in equilibrium:
• sum of anticlockwise moments = sum of clockwise moments

Question 4

Seatbelts in terms of pressure TEMPLATE

Answer 4

• seat belt stretches (during collision)…
• which increases the area over which the force acts
• so pressure on body reduces (since p = f/a)

Question 5

Seatbelts in terms of force and momentum TEMPLATE (or any other safety apparatus/ feature)

Answer 5

• same momentum change
• increased impact time
• which reduces rate of change of momentum
• so it reduces the average force (since F = 𝚫p / t)

ADDITIONAL POINT:

• seatbelts mean passenger stays on seat / is not thrown from vehicle

Question 6

What safety features does car have (3)

Answer 6

• air bags
• crumple zones
• seatbelts

Question 7

Define centre of gravity

Answer 7

The point in a body where the entire weight of the body can be considered to act.