How Do You Calculate the Momentum of a Puck After a Collision?

[rrosa522]

Homework Statement

A hockey player passes a puck with an average force of 250N. The hockey stick is in contact with the puck for 0.0030s, and the mass of the puck is 180g. The puck is not moving before the player hits it.

a) Determine the impulse imparted by the hockey stick.
b)Calculate the momentum of the puck as a result of the collision

Homework Equations

p=mv

The Attempt at a Solution

I got 0.75 kg*m/s for the part A but I don't know what to do for part B. Shouldn't the answer be the same for both. I really don't understand the difference between both questions.

 

[Doc Al]

I really don't understand the difference between both questions.

They want to see if you understand the relationship between impulse and momentum. Sounds like you do.

Shouldn't the answer be the same for both.

Yes, in this case. But what if the puck was at rest when it was hit?

 

[rrosa522]

They want to see if you understand the relationship between impulse and momentum. Sounds like you do. Yes, in this case. But what if the puck was at rest when it was hit?

how can I find the momentum without knowing the velocity, the answer should be 4.2kg*m/s

 

[Doc Al]

how can I find the momentum without knowing the velocity,

You know the impulse, which is all you need. Review the impulse-momentum theorem.

the answer should be 4.2kg*m/s

Why do you think that? Your initial answer was correct.

 

[rrosa522]

You know the impulse, which is all you need. Review the impulse-momentum theorem.Why do you think that? Your initial answer was correct.

yes, but the answer in my book is 4.2. I just want to know if it is a mistake.

 

[Doc Al]

yes, but the answer in my book is 4.2. I just want to know if it is a mistake.

Looks to me like the book is mistaken.