A weight - lifter lifts a bell weighing(2 000 N) and holds it in the air for (5 seconds. Has he done any work? Explain your answer. ​

How does the amount of energy required to hold each proton and neutron in the nucleus compare to the energy released when they are removed?

If the area of a square has increased by a factor of 16, by how much has each side increased?

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.