Problem 1-5

1-5. A sandbag is dropped from a hot air balloon. The net effect of both aerodynamic drag  and gravity is to produce an acceleration a_y = g – cv²  where c (equal to 6.00×10^-4 m^-1) is a drag coefficient with units of m^-1 when v is expressed in m/s. The positive y direction is downward. Determine the sandbag’s speed after it has fallen 400 m.