Hail comes straight down at a mass rate of m/δt = 0.050 kg/s and an initial velocity of v0 = -15 m/s and strikes the roof perpendicularly. unlike rain, hail usually does not come to rest after striking a surface. instead, the hailstones bounce off the roof of the car. suppose that the hail bounces off the roof of the car with a velocity of +15 m/s. ignoring the weight of the hailstones, calculate the force exerted by the hail on the roof.