Question

A boy of mass $m$ climbs up a staircase of vertical height $h$. What is the work done by the boy against the force of gravity?

• A. $mh$
• B. $mg$
• C. $\frac{m{h}^2}{2}$
• D. $mgh$

Answer 1

The correct option is D $mgh$

For objects near the earth the acceleration of gravity $g$ can be considered to be approximately constant and the expression for potential energy relative to the Earth's surface becomes $U=mgh,$ where $h$ is the height above the surface and $g$ is the surface value of the acceleration of gravity.
That is, the work done by the boy against the force of gravity is $mgh$.