question_answer 18)

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 trolley's floor at the rate . What is the speed of the trolley after the entire sand bag is empty ?  

Answer:

Here P.E. of the bob at K.E. of the bob at As 5% of the P.E. is dissipated against air resistance, so of or              or              .