P5 - Forces 4 Momentum

Question 1

State the equation ised to calculate an object’s momentum

Answer 1

Momentum = mass x velocity

Question 2

What is the unit used for momentum ?

Answer 2

kg m/s

Kilogram metres per seconds

Question 3

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

Answer 3

The total momentum before is equal to the total momentum afterwards

Question 4

State an equation linking change in momentum, force and time

Answer 4

Force x time = change in momentum

Question 5

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

Answer 5

The rate of change of momentum

Question 6

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

Answer 6

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

Question 7

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

Answer 7

• 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

Question 8

If an object is not moving

Answer 8

Then the momentum is zero