3. A railroad bumper is designed to slow down a rapidly moving railroad car. After a 20,000kg railroad car traveling at 20m/s engages the bumper, its displacement x (in meters) and velocity v (in m/s) as a function of time t (in seconds) is given by: x = 4.219(e-1.58t-e-6.32t) u(t) = 26.67e-6.32t-6.67e-1.58t Figure 2: Bumper