Sand drops onto the 2-Mg empty rail car at 50 kg>s from a conveyor belt. If the car is initially coasting at 4 m>s, determine the speed of the car as a function of time

Try b? sorry if i’m incorrect

Kinetic energy = 1/2mv^2. since the mass is constant we can form a ratio of it's kinetic energy at 60 divided by that at 30 to see ke(60)/ke(30) = +(60^2)/30^2). this may be said to 300% increase.