A billiard ball is rolling at a speed of 1.2 m / s and collides with a resting ball, after the impact, the first ball stops

A billiard ball is rolling at a speed of 1.2 m / s and collides with a resting ball, after the impact, the first ball stops, and the second begins to move at a speed of 2.4 m / s. Determine the mass of the second ball if the mass of the first is 200 g.

V1 = 1.2 m / s.

V2 = 0 m / s.

V2 “= 2.4 m / s.

V1 “= 0 m / s.

m1 = 200 g = 0.2 kg.

m2 -?

We will assume that in the interaction of billiard balls, the friction force can be neglected. Two balls, which interact only with each other, can be considered a closed system for which the law of conservation of momentum is valid: m1 * V1 + m2 * V2 = m1 * V1 “+ m2 * V2”.

Since by the condition of the problem V2 = 0 m / s and V1 “= 0 m / s, then m1 * V1 = m2 * V2”.

m2 = m1 * V1 / V2 “.

m2 = 0.2 kg * 1.2 m / s / 2.4 m / s = 0.1 kg.

Answer: the second billiard ball has a mass m2 = 0.1 kg.