A ball with a mass of 2 kg rolls at a speed of 3 m / s and hits another ball that is at rest after the impact

A ball with a mass of 2 kg rolls at a speed of 3 m / s and hits another ball that is at rest after the impact, both balls roll in the same direction in which the first ball was rolling. If the first continued to move at a speed of 0.5m / s, and the second 8m / s, then what is the mass of the second ball?

m1 = 2 kg.

V1 = 3 m / s.

V2 = 0 m / s.

V1 “= 0.5 m / s.

V2 “= 8 m / s.

m2 -?

Let’s write down the law of conservation of momentum: m 1 * V1 + m2 * V2 = m 1 * V1 “+ m2 * V2”, where m 1, m2 are the masses of the balls, V1, V2 are the velocities of the balls before impact, V1 “, V2” are the velocities balls after impact.

Since the second ball was immovable, V2 = 0 m / s.

m 1 * V1 = m 1 * V1 “+ m2 * V2”.

The formula for determining the mass of the second ball m2 will be: m2 = m 1 * (V1 – V1 “) / V2”.

m2 = 2 kg * (3 m / s – 0.5 m / s) / 8 m / s = 0.625 kg.

Answer: the second ball has a mass m2 = 0.625 kg.