A 70 kg skateboarder starts at rest at the top of an 18-m high ramp. He rolls down the ramp and then up a 10-m high rise on the other side. One of the wheels on his skateboard is faulty, so it exerts a constant 40 N force that opposes his motion as he moves. All other friction 18 m and drag forces are negligible. The total distance 10 m traveled by the skateboarder is 45 m. What is his speed when he reaches the top of the 10-m rise