# Physics Question?

A white billiard ball of mass 5 kg is traveling at 5 m/s, when it collides and sticks to a black billiard of the same mass,(a) what is their resulting velocity? (b) What is their total momentum before and (c) after the collision?

I'd like to know how these answers are gotten more than the answer itself.

Don't ask me how a billiard ball sticks to another billiard ball- I didn't write the question.

### 1 Answer

- NCSLv 71 month agoFavorite Answer
The answers are obtained through conservation of momentum.

initial Σ mass * velocity = final Σ mass * velocity

Your initial system momentum is

p = 5kg * 5m/s = 25 kg·m/s

Since momentum is conserved for all collisions for which there is no external force (which we'll assume here), the final momentum is the same as the initial momentum.

You should be able to determine the final velocity when the two equal masses stick together.

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