Two balls weighing 100 and 200 g move towards each other. With what speed will these balls move and in what direction

| January 8, 2021 | education

Two balls weighing 100 and 200 g move towards each other. With what speed will these balls move and in what direction if, after impact, they move as a whole? The velocities of the balls before impact are 4 and 3 m / s, respectively.

m1 = 100 g = 0.1 kg.
m2 = 200 g = 0.2 kg.
V1 = 4 m / s.
V2 = 3 m / s.
V “-?
Let us write the law of conservation of momentum for a closed system of two balls in vector form: m1 * V1 + m2 * V2 = m1 * V1 “+ m2 * V2″, where m1, m2 are the masses of the balls, V1, V2 is the speed of the balls before collision, V1 ” , V2 “- the speed of the balls after collision.
Since the balls after impact move as a whole, their speeds after impact will be the same: V1 “= V2” = V “.
The impulse conservation law will take the form: m1 * V1 – m2 * V2 = (m1 + m2) * V “.
V “= (m1 * V1 – m2 * V2) / (m1 + m2).
V “= (0.1 kg * 4 m / s – 0.2 kg * 3 m / s) / (0.1 kg + 0.2 kg) = – 0.66 m / s.
The “-” sign means that the velocity after the collision is directed towards the movement of the second ball before the impact.
Answer: V “= 0.66 m / s.



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