The potential energy of an object with respect to the ground is given by:
[tex]U=mgh[/tex]
where m is the mass of the object, g is the gravitational acceleration, and h is the height of the object with respect to the ground.
In this problem, the mass of the anvil is m=20 kg and the height above the ground is h=3 m, therefore the potential energy of the anvil is
[tex]U=mgh=(20 kg)(9.81 m/s^2)(3 m)=588.6 J[/tex]
