A trolley of mass 300 kg carrying a sandbag of 25 kg is moving uniformly with a speed of 27 km/h on a frictionless track. After a while, sand starts leaking out of a hole on the floor of the trolley at the rate of 0.05 kg s–1. What is the speed of the trolley after the entire sand bag is empty?
The trolley, at first, is moving with a constant velocity. Hence, there is no net external force acting on the trolley. Even if the sand starts leaking, there is no external force on the trolley. Hence, the speed of the trolley will not change.