Module 3 - Section 5 - Momentum And Impulse

Question 1

Whats the base unit for momentum ?

Answer 1

kgms*-1

Question 2

What’s the equation for momentum ?

Answer 2

Momentum = mass x velocity
P=mv

Question 3

What’s the conservation of momentum ?

Answer 3

The conservation of momentum states that the total momentum of two objects before they collide is equal to the total momentum after they collide

Question 4

What is a perfectly elastic collision ?

Answer 4

A perfectly elastic collision is one where the momentum is conserved and kinetic energy is conserved - meaning that no energy is dissipated as heat, sound etc

Question 5

What is an inelastic collision ?

Answer 5

If the collision is inelastic then it means that some of the kinetic energy is converted into other forms during the collision ( some Ke is dissipated in top the surroundings ) - However MOMENTUM IS ALWAYS CONSERVED

Question 6

What is impulse ?

Answer 6

Impulse is the change of momentum
OR
It’s defined as the average force x time

The unit for impulse are Newton Seconds - Ns

Question 7

Whats another equation for Momentum ?

Answer 7

Momentum = Force x change in time
p = F x t

Question 8

Why does impulse ( Ft ) = momentum ?

Answer 8

Because of Newton’s second law of motion - F = P / t
- If you rearrange this then you get p = F x t

And impulse = ft
So P = ft

Question 9

How can you calculate impulse (ft) on a FORCE TIME GRAPH?

Answer 9

The area is equal to the impulse

Question 10

What do all moving objects have ?

Answer 10

Momentum

Question 11

Explain Newton’s second law ( long way )

Answer 11

Newton’s second law states that the resultant force acting on the object is directly proportional to the rate of change of momentum ( which is p/t ) and this means that the Rf will change in response to the change of momentum so it means how much does the momentum change for e,g, in 10secs and this would impact the Rf - also the momentum is equal to mv - so the resultant force of the object is equal to the rate of change of its mass and velocity so if the velocity changes then then the Rf that acts on the object will change and this is also with mass - although it’s usually the velocity that changes and not the mass - and if the mass is constant then you could just use the equation F = ma

Question 12

What happens if an object has a lot of momentum ?

Answer 12

It will be more difficult to stop

Question 13

When does the law of conservation of momentum only work ?

Answer 13

It only works in a closed system where no external forces act