A trolley of 300 kg carrying a sand bag 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 trolleys floor at the rate of 0.05 kg${{s}^{-1}}$. What is the speed of the troll



As the trolley carrying the sand bag moving uniformly, therefore, external force on system = zero. - 1
When the sand leaks out, it does not lead to application of any external force on the trolley. Hence, the speed the trolley shall not change. So, speed will remain same
speed = 27 km/h.