Suppose a child drives a bumper car head on into the side rail, which exerts a force of 4000 n on the car for 0.200 s. (a) what impulse is imparted by this force? (b) find the final velocity of the bumper car if its initial velocity was 2.80 m/s and the car plus driver have a mass of 200 kg. you may neglect friction between the car and floor.

The impulse is the force multiplied by the time. So we have I = Ft. F = 400N t = 0.2s. Hence the impulse is 400 * 0.2 = 80 Ns. Bear in mind that Impulse is just the change in momentum. We need to calculate the change in momentum. Momentum before collision is, P1 = mv where m and v are the mass and velocity. So we have P1 = 200 * 2.8 = 560 kgm/s While the final momentum P2 = 200 * v. Note v is our sought out velocity. But then we have final momentum - initial momentum = Impulse. So we have 200v - 560 = 80. 200v = 80 + 560 = 640. Hence v which is the final velocity is 640/200 = 3.2 m/s.