P10.7 Safety first

Question 1

How can safety helmets keep you safe?

Answer 1

The helmet is designed to increase the impact time. With a longer impact time the rate of change of momentum per second is reduced

Question 2

How can seat belt keep people safe?

Answer 2

Time taken to stop someone in a car is longer if they are wearing a seat belt
Seat belt acts across the chest, so it spreads the force out

Question 3

How do air bags keep people safe?

Answer 3

Spread the force of an impact across the upper part of a person’s body. It also icnreases the impact time

Question 4

How can cushioned surfaces reduce the risk of danger?

Answer 4

The duration of the impact is longer than it would be if the surface had been hard like concrete. So the person’s momentum is reduced to zero over a longer time by the cushioning effect. Change of momentum per second is therefore reduced.