After this experiment was done the mechanical energy-time graph showed a fairly straight line. It showed this line because gravity, a conservative force, was used to move the cart. Since the force was conservative, the mechanical energy throughout the experiment stayed the same, with no energy being lost or gained. The gravitational potential energy is being transferred to kinetic energy since the object is not at a rest and is moving down the ramp, as shown in the kinetic energy-time graph and potential energy-time graph. Since the energy remains constant throughout the whole run, gravity is a force which is conservative.