1. A mass of 3.0 kg is subject to a force F(x) = 8.0 N - (4.0 N/m)x The potential energy of the mass is zero at x = 0. What is the potential energy of the mass at x = 2.0 m?
2. At what rate is a 60.0kg boy using energy when he runs up a flight of stairs 10.0m high, in 8.00s?