A stone is accidentally released from the top of a tall building
PHYSICS · Multi-part · CBSE · Physics · Work and Energy · Work and Energy
Problem
A 0.5kg stone is accidentally released from the top of a 20m tall building. It passes a window ledge that is 12m above the ground and is caught instantaneously by a worker standing there. The worker then throws the stone straight back up so that it just reaches the original point of release.
(i) Taking the ground as the zero level, calculate the change in gravitational potential energy of the stone as it falls from the top of the building to the ledge.
(ii) How much work is done by the force of gravity on the stone during this fall?
(iii) Determine the work the worker must do on the stone to return it from the ledge to the top of the building.
(iv) After the stone completes the entire cycle described above, what is the net change in its gravitational potential energy with respect to the ground? State a reason for your answer.