# What is the gravitational potential energy of a  9 kg object on a shelf  8/9 m  high?

May 10, 2018

Gravitational Potential Energy $U$ is energy stored by our system in doing work against the gravitational force (or Weight, $W = m g$) lifting an object to a certain height $h$ with respect, say, the ground taken as zero reference.
$W = m g h = \cancel{9} \cdot 9.8 \cdot \frac{8}{\cancel{9}} = 78.4 J$