Ball 1, with a mass of 10kg, is moving to the right at 20 m/s. Ball 2 is moving to the left at 20 m/s. Upon collision, ball 2 comes to a standstill, and ball 1 moves to the left at twice its origional speed. What is the mass of ball 2?.

For us to know the mass of ball 2, we will be using the law of momentum conservation which is the momentum before collision and the momentum after collision (m1 v1 + m2 v2 = m1 v1 + m2 v2):

(10*20) + (m * - 20) = (10 * - 40) + (m*0)

200 - 20m = - 400

Since we are looking for "m" which is the mass of ball 2, derivation will be needed.

Then:

m = ( - 400-200) / ( - 20) = 30 kg

Therefore, it is concluded that the mas for ball 2 is 30kg.