On a trolley weighing 50 kg, rolling along a horizontal track at a speed of 0.2 m / s, 200 kg of crushed stone is poured on top.

On a trolley weighing 50 kg, rolling along a horizontal track at a speed of 0.2 m / s, 200 kg of crushed stone is poured on top. How much has the trolley speed decreased?

In this problem, we use the law of conservation of energy. So our impulse before should be equal to AFTER. This means that we had 50 * 0.2 = 10 kg * m / s TO, and the speed after pouring rubble will be how to divide the entire impulse by the total mass. Otherwise, it turns out 10/250 = 0.04 m / s. Next, we find the difference in speed – this will be our answer. 0.2-0.04 = 0.16 m / s