Answer :
To solve this problem we will apply the concepts related to gravitational potential energy.
This can be defined as the product between mass, gravity and body height.
Mathematically it can be expressed as
[tex]\Delta P = mgh[/tex]
[tex]\Delta P = (8.7)(9.8)(3)[/tex]
[tex]\Delta P = 255.78J[/tex]
Therefore the change in the internal energy of the system is 255.78