A box initially with mass m0 kilograms and having a large granular powder falls out of cargo plane. But the box has a hole at the top which allows material to escape as the box falls. Assume that the rate the powder leaks is "a" kilograms per second. Assume the box falls without tumbling and that the loss of powder at the top does not directly affect the box's speed. Assume that the air resistance is proportional to the velocity with constant of proportionality"k". Assume that k/a <2. Model this situation and solve the resulting initial value problem to find the velocity of the box.