5.7 - momentum

Question 1

What is the unit used for momentum?

Answer 1

kilogram metres per seconds

Question 2

In a closed system, what can be said
about the momentum before and after a
collision?

Answer 2

The total momentum before is equal to
the total momentum afterwards.

Question 3

What quantity is equal to the force
experienced in a collision?

Answer 3

The rate of change of momentum.

Question 4

If an object’s change of momentum is
fixed, what is the only way to reduce the
force that the object experiences?

Answer 4

Increase the length of time over which
the change of momentum occurs.

Question 5

Explain how a seatbelt improves a
passenger’s safety during a collision

Answer 5

● Passenger must decelerate from the vehicle’s velocity at impact
to zero, meaning they undergo a fixed change of momentum
● The force they experience is equal to the rate of change of
momentum
● Seatbelts increase the time over which the force is applied,
reducing the rate of change of momentum and therefore
reducing the force experienced