Preston pushes a wheelbarrow weighing 500 N to the top of a 50 m ramp, inclined 20° with the horizontal, and leaves it. Tamara accidentally bumps the wheelbarrow. It slides back down the ramp, during which an 80 N frictional force acts on it over the 50 m. What is the wheelbarrow's kinetic energy at the bottom of the ramp? (g = 9.8 m/s2) * 4550 J * 6550 J * 8150 J * 13100 J I am really confused with this one. I need help. Please get back to me a.s.a.p. with some explanations or anything that will be helpful. I don't even know where to start. Thanks.