Question

50 J of work must be done to lift a vase from the ground up on to a shelf. a When the vase is on the shelf, what is its gravitational potential energy? b If the vase falls from the shelf, how much kinetic energy does it have just before it hits the ground? (Assume that air resistance is negligible.) c What happens to this energy after the vase has hit the ground?

Answer 1

(a) The gravitational potential energy of the vase on the shelf

$$E_{pi}=50\;\rm{J}$$

(b) The law of conservation of energy gives

$$E_{kf}=E_{pi}=50\;\rm{J}$$

(c) When the vase has hit the ground, it energy would be transferred to the ground.