1. Calculate the potential energy of a book with a mass of 1.5 kilograms, sitting on a shelf that is 2.3 meters high. 2. A boy with a mass of 65.9kg is on a high diving board 4.55 meters high. What is his potential energy? 3. A rock with a mass of 23kg rolls down a hill at a speed of 15 meters per second. Calculate its kinetic energy. 4. What is the kinetic energy of an object moving at a speed of 2.8 meters per second, and has a mass of 17.5kg