The trolley carrying a sandbag is moving with a uniform speed of 27 kmh-1. It implies that the system of trolley and the sandbag is not acted upon by any external force. If the sand leaks out of a hole on the trolley's floor, it does not lead to application of any external force, on the trolley. Therefore, speed of the trolley will not change as the sand leaks out or even after the sandbag becomes empty.
