Ball a of mass 5.0 kilograms moving at 20 meters per second collides with ball b of unknown mass moving at 10 meters per second in the same direction. after the collision, ball a moves at 10 meters per second and ball b at 15 meters per second, both still in the same direction. what is the mass of ball b? * 1 point your answer

10.0 kg

Explanation:

The problem can be solved by applying the law of conservation of momentum - the total momentum before the collision must be equal to the total momentum after the collision:

where:

is the mass of ball A

is the velocity of ball A before the collision

is the mass of ball B

is the velocity of ball B before the collision (same sign of uA, since they are moving in same direction)

is the velocity of ball A after collision

is the velocity of ball B after collision

Re-arranging the equation, we can solve to find mB, the mass of ball B: