On a wagon weighing 800 kg, moving at a speed of 0.2 m / s, 200 kg of crushed stone

On a wagon weighing 800 kg, moving at a speed of 0.2 m / s, 200 kg of crushed stone was poured to the extent that the speed of the wagon was changed.

Task data: m1 (mass of a moving trolley) = 800 kg; V1 (trolley speed before loading rubble) = 0.2 m / s; m2 (crushed stone mass) = 200 kg.

1) Determine the speed of the trolley after loading rubble: m1 * V1 = (m1 + m2) * V1.2, whence V1.2 = m1 * V1 / (m1 + m2) = 800 * 0.2 / (800 + 200) = 0.16 m / s.

2) Let us calculate the change in the speed of the trolley: ΔV = V1 – V1.2 = 0.2 – 0.16 = 0.04 m / s.

Answer: After loading the crushed stone, the speed of the trolley decreased by 0.04 m / s.