1. A 2.0 kg mass is lifted 4.0 m above the ground. Find the change in gravitational energy. 2. 40.0 Joules of energy are expended to drag a classmate 4.0 m across a oor at constant velocity. Sketch and label a force diagram below. Find the frictional force on the classmate. 3. A car accelerates from 30 mi/hr to 60 mi/hr. How many times greater is the car's kinetic energy at the higher speed compared to the kinetic energy at the slower speed? 4. How much time would it take a train locomotive running at 6000. Horsepower to use the 132 million Joules of energy in a gallon of diesel fuel? (1 Hp = 746 Watts) 5. How many kilowatthours of energy does a 100. Watt light bulb use when left on continuously for 50. hours? 6. What does the following series of energy pie charts tell you about the motion of a skateboarder? Explain. mmmmm