What is the gravitational potential energy of a  49 kg object on a shelf  7/4 m  high?

May 9, 2016

$840.35 J$
The gravitational PE of an object of mass, $m = 49 k g$ at height $h = \frac{7}{4} m$ is the work done by an agent to lift the body to that heigt from the ground.
So PE= Work done = $\text{Force"xx} \mathrm{di} s p l a c e m e n t = m \times g \times h$
$= 49 \times 9.8 \times \frac{7}{4} J = 840.35 J$