A person lifts a suitcase from the floor and places it on a table....

By the work-energy theorem, the net work done on the suitcase is equal to its change in kinetic energy.

Since the suitcase starts from rest on the floor and comes to rest on the table, the change in kinetic energy is zero.

$W_{\text{net}} = W_{\text{person}} + W_{\text{gravity}} = 0$

$W_{\text{person}} = -W_{\text{gravity}}$

The work done by gravity is $-mgh$, where $mg$ is the weight of the suitcase and $h$ is the height of the table.

$W_{\text{person}} = mgh$

This shows that the work done by the person on the suitcase depends only on the weight of the suitcase and the vertical displacement.

It does not depend on the time taken to lift it, the weight of the person, or the path taken by the suitcase (since gravity is a conservative force).