Hail comes straight down at a mass rate of m/?t = 0.070 kg/s and an initial velocity of v0 = -13 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 +13 m/s. Ignoring the weight of the hailstones, calculate the force exerted by the hail on the roof.