collisions, explosions and impulse

Question 1

What is the momentum of an object?

Answer 1

The momentum of an object is simply its mass times its velocity. (symbol ‘p’)
Momentum is a vector
p=mv

Question 2

What is the law of conservation of momentum?

Answer 2

in the absence of external forces the total momentum before the collision equals the total momentum after the collision

Question 3

How di you set up momentum questions?

Answer 3

mAuA+mBuB=mAvA+mBvB

velocity needs a constant sign convention

Question 4

What happens with elastic collisions?

Answer 4

the total kinetic energy of both objects is equal before and after the collision (kinetic energy is conserved)

Question 5

What happens with inelastic collisions?

Answer 5

the total kinetic energy of both objects less after the collision than it was before (kinetic energy is not conserved)

Question 6

How do you work out explosion questions?

Answer 6

An explosion question is exactly the same only the total momentum before the collision is zero!
Therefore the total momentum afterwards must also be zero.
Kinetic energy is gained

Question 7

What is impulse?

Answer 7

When an object experiences an unbalanced force for a short period of time it experiences an impulse. This causes the momentum of the object to change

Question 8

How do you calculate impulse?

Answer 8

Ft=mv-mu
Impulse+ change in momentum

Impulse=average force x time

Question 9

What is impulse equal to?

Answer 9

area under graph of force by time graph and the change in momentum of an object involved in the interaction

Question 10

Describe force-time graphs

Answer 10

When an object receives an impulse, it experiences a force for a very short time.
Impulse = average force x time
This force rises quickly to a maximum and then quickly falls to zero