Question

In a completely elastic collision, m1 = 10 kg is traveling from left to right at a speed 10 m/s and collides with m2 = 5 kg traveling at a speed of 14 m/s traveling toward it. After collision, what is the velocity of the first ball to the nearest tenth of a m/s, if the second ball's velocity is 14 m/s?

I ended up getting 10.0 m/s, but it was wrong. Can someone show me where I went wrong?

Answer 1

@zephyr141 -- would it help if I showed you the steps that I took to get my answer first?

Answer 2

no i see what you did

Answer 3

you set m1's velocity to negative.

Answer 4

m1 is traveling from left TO RIGHT so it should be positive

Answer 5

\[(10*10)+[5*(-14)]=10v_{1}+(5*14)\] i'm assuming here that the second 14 m/s is the final velocity of ball 2

Answer 6

This is what I wrote down for the information given (just trying to understand this so sinks in): \[m _{1} = 10 kg \]\[m_{2} = 5 kg\] \[v_{1} = 10 m/s\]\[v_{2}= -14 m/s\]\[v_{2}^{f} = -14 m/s\]

Answer 7

is the that all written down word for word? if so then i think that the final velocity of ball 2 is positive 14m/s.

Answer 8

i mean the question

Answer 9

Yes. That is exactly how it was written.

Answer 10

then i think the final velocity, or v2 final, is going to be positive 14 m/s

Answer 11

Oh... wait, would that because because after the collision.. the 2nd ball would go in the opposite direction?

Answer 12

yeah. you typed it out exactly as it was given, as you said, so i think it's going in the positive direction after the collision.