Question

A 40.0-kg student climbs up a ladder to the roof of a building. The gravitational potential energy of the student at this point is 2.00 x 103 J. How high is the student above the ground?

Answer 1

By definition, the potential energy is:

$$E = mgh$$

where $m = 40kg$ is the mass of the student, $g = 9.81m/s^2$ is the gravitational acceleration, $h$ is the height. Substituting $E = 2\times 10^{3}J$ and expressing $h$, obtain:

$$h = \dfrac{E}{mg} = \dfrac{2\times 10^3}{40\cdot 9.81} \approx 5.10m$$

Answer. 5.10 m.