A ball weighing 8 grams, flies at a speed of 2 m / s onto a resting ball weighing 40 grams

A ball weighing 8 grams, flies at a speed of 2 m / s onto a resting ball weighing 40 grams. Considering the blow to be absolutely inelastic. Find the speed of the body after impact.

Let us designate the data m1 = 8 gr = 0.008 kg, m2 = 40 gr = 0.04 kg, v1 = 2m / s, v2 = 0; v ‘-?

According to the law of conservation of momentum of inelastic impact: m1 * v1 = (m1 + m2) * v ‘.

On the left side of the equation, it is not written about the second body, since its momentum is 0.

We get v ‘= m1 * v1 / (m1 + m2) = 0.008 * 2 / (0.008 + 0.04) = 1/3 m / s = 0.33 m / s