Which of these is an example of mechanical energy transforming into heat energy?
a. burning gasoline
b. sunbathing by the pool
c. lightning creating thunder
d. rubbing your hands together

How is the gravitational force related to the distance between two objects?

Two masses are connected by a rope that hangs over a pulley as shown below. the pulley is a uniform cylinder of radius 푅=0.381meters and mass 푀=3.1푘푔. initially 푚"is on the ground and 푚#rests 2.5 meters above the ground. if the system is released, use conservation of energy to determine the speed of 푚#just before it strikes the ground. assume the pulley bearing is frictionless.

What type of force holds atoms together in a crystal?