1.25 1.00- .. .. . . . . . . . . 0.75 0.50 Velocity (m/s) 0.25 0.00 -0.25- -0.50 -0.75+ 0.00 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 2.25 2.50 Time (s) A group of students conducts an experiment in which they use motion sensors to measure the velocity of a cart of mass M as it rolls down a track inclined at an angle O relative to horizontal. The cart then makes a smooth transition onto a horizontal section of the track and moves to the right along the track. At the end of the horizontal section is an elastic bumper with which the cart collides and rebounds. The graph of velocity as a function of time for the entire motion of the cart is shown. There is negligible friction between the cart and the track.\f