# physics =)

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A 0.200 kg plastic ball moves with a velocity of 0.30 m/s. It collides with a second plastic ball of mass 0.100 kg, which is moving along the same line at a speed of 0.10 m/s. After the collision, both balls continue moving in the same, original direction. The speed of the 0.100 kg ball is 0.26 m/s. What is the new velocity of the 0.200 kg ball?

You can solve for that with the conservation of momentum equation (for motion along one axis only) but my question is how you do that?

Before impact

m = 0.200 kg
v = 0.30 m/s
p = 0.06

m = 0.100 kg
v = 0.10 m/s
p = 0.01

After impact

m = 0.200 kg
v = ?

m = 0.100 kg
v = 0.26 m/s
p = 0.026

Now, I'm a little confused on how to find the velocity should i use the same momentum but then although mass doesnt change that doesnt mean momentum doesnt change.

• physics =) - ,

Original momentum = .06+.01 = .07
that is also the final momentum
.07 = .2*v + .026

• physics =) - ,

Ok, thanks a lot! Merry christmas and a happy almost new yr

• physics =) - ,

thanks! merry christmas

• physics =) - ,

You are welcome. Happy New Year and Merry Christmas !