Question

You are re-shelving books in a library. You lift a book from the floor to the top shelf. The kinetic energy of the book on the floor was zero and the kinetic energy of the book on the top shelf is zero, so no change occurs in the kinetic energy, yet you did some work in lifting the book. Is the work–kinetic energy theorem violated? Explain.

Short answer

The work-kinetic energy theorem is not violated since the acquired kinetic energy gets converted to potential energy on the top shelf.

Step-by-step solution

Given data

Kinetic energy of a book on the floor and on top of shelf is zero.

Change in potential

The total kinetic energy and potential energy of a system is conserved.

Determining the energy change in a book when picked up

The work done by a person to pick up a book from the ground is indeed converted to its kinetic energy which increases as it is moved up from the ground. When it is kept in the top shelf the acquired kinetic energy gets converted to potential energy which is non-zero on the top shelf because of its height. Thus the work-kinetic energy theorem is not violated.