The question doesn't provide enough information to give an answer, but I'm assuming the characteristics of the tank and then you can replicate this approach to answer your own problem.
Answer:
[tex]U=43,790\ J[/tex]
Explanation:
Potential Gravitational Energy
It's the capacity of an object to do work due to the vertical distance respect to a fixed reference. If an object of mass m is placed at a height h from ground level, it's potential energy is
[tex]U=mgh[/tex]
We know the water in a tank is positioned 5 feet above the ground level. It gives us
[tex]h=5\ ft=5/3.281=1.524\ m[/tex]
We need to know the mass of water suspended in the tank. Since the problem doesn't give any clue about it, we'll assume a spheric tank of 1-meter radius, 70% filled with water.
The volume of a sphere is
[tex]\displaystyle V=\frac{4\pi r^3}{3}[/tex]
The volume of water in our tank is
[tex]\displaystyle V=0.7\frac{4\pi 1^3}{3}=2.932\ m^3=2,932\ lt[/tex]
Since 1 liter of water has a mass of 1 kg, then
[tex]m=2,932\ kg[/tex]
And the potential energy is
[tex]U=(2,932\ kg)(9.8\ m/s^2)(1.524\ m)[/tex]
[tex]\boxed{U=43,790\ J}[/tex]
