A trolley weighing 400 kg moves at a speed of 4 m / s from above a load weighing 200 kg

| March 20, 2021 | education

A trolley weighing 400 kg moves at a speed of 4 m / s from above a load weighing 200 kg falls at a speed of 1 m / s. How fast will the loaded cart move?

mt = 400 kg.

Vt = 4 m / s.

mg = 200 kg.

Vg = 1 m / s.

V -?

For the movement of a cart with a load, the law of conservation of momentum is valid in vector form: mt * Vt + mg * Vg = (mt + mg) * V.

1) Consider that the speed of movement of the load before falling Vg directed towards the movement of the trolley: mt * Vt + mg * Vg = (mt + mg) * V.

V = (mt * Vt + mg * Vg) / (mt + mg).

V = (400 kg * 4 m / s + 200 kg * 1 m / s) / (400 kg + 200 kg) = 3 m / s.

2) Consider that the speed of movement of the load before falling Vg is directed in the opposite direction of the movement of the trolley: mt * Vt – mg * Vg = (mt + mg) * V.

V = (mt * Vt – mg * Vg) / (mt + mg).

V = (400 kg * 4 m / s – 200 kg * 1 m / s) / (400 kg + 200 kg) = 2.3 m / s.

Answer: after the fall of the load, the trolley with it can move at a speed of V = 3 m / s or V = 2.3 m / s.



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