# Physics 11 problem 16

This is really easy stuff, but im really confused. I have a couple other questions as well. If theres anyone who's really good with momentum than do you think you could spend a little while to help me out? alright well heres one problem.

A 95kg fullback, running at 8.2m/s, collides in midair with a 128-kg defensive tackle moving in the opposite direction. Both players end up with zero speed.
a) what was the fullbacks momentum before the collision...(I came up with 779-kg*m/s)

B) what was the change in the fullbacks momentum?

C) what was the change in the tackles momentum?

D) what was the tackles original momentum?

E)how fast was the tackle originally moving?

## Answers and Replies

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EP
Well, you know your original fullbacks momentum and his final momentum. So what is the "change" in his momentum?

-779? how do i do the rest of the problem though?

EP
Well if they come to a complete stop, what has to be true?

that they don't have any momentum anymore?

EP
What does that mean about thier original momentum?

Im not sure. Im confused

EP
Write out a conservation of momentum equation for the problem and see how you might get no net velocity after the collision.

the only equations my teacher gave us was p=Ft and p=mv

EP
P(tackle)+ P(fullback)= P' (Tackle-Fullback system)

oh ok. So the tackles original momentum is -779? and he was originally moving at -6.1m/s?

EP
yes, thats right!

and the change in momentum is 0?

EP
The change in the momentum of the tackle? What was his original p and what was his final p.

his original p=-779 and his finalp=0

EP
So whats his change in p