Balls weighing 5 kg and 1 kg move towards each other at speeds of 5 m / s each. After the central blow

| May 6, 2021 | education

Balls weighing 5 kg and 1 kg move towards each other at speeds of 5 m / s each. After the central blow, the balls continue to move in one direction, and the speed of the first ball is 2m / s. Determine the speed of the second after impact.

m1 = 5 kg.
m2 = 1 kg.
V1 = V2 = 5 m / s.
V1 “= 2 m / s.

V2 “-?

Let us write down the law of conservation of momentum for balls upon impact: p1 + p2 = p1 “+ p2”.
р1 = m1 * V1, р2 = – m2 * V2.
The “-” sign means that the speed of the balls before impact has the opposite direction.
p1 “= m1 * V1”, p2 “= m2 * V2”.
m1 * V1 – m2 * V2 = m1 * V1 “+ m2 * V2”.
V2 “= (m1 * V1 – m2 * V2 – m1 * V1”) / m2.
V2 “= (5 kg * 5 m / s – 1 kg * 5 m / s – 5 kg * 2 m / s) / 1 kg = 10 m / s.
Answer: the speed of the second ball after impact will be V2 “= 10 m / s.



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