Question

What is the gravitational potential energy of a 150 kg object suspended 5m above the Earth's surface

Answer 1

The gravitational potential energy referred to the ground level is given by
$U=mgh$
where m is the mass of the object, $g=9.81 m/s^2$ is the gravitational acceleration and h is the height of the object with respect to the ground.

Therefore in our problem the potential energy is
$U=(150 kg)(9.81 m/s^2)(5 m)=7357.5 J$