Calculating Gravitational Potential Energy of a Hanging Ball

[gansta344u]

Homework Statement

A 2.35 kg ball is attached to a ceiling by a
1.92 m long string. The height of the room is
5.92 m .
The acceleration of gravity is 9.8 m/s2 .
What is the gravitational potential energy
associated with the ball relative to the ceiling?
Answer in units of J

What is its gravitational potential energy rel-
ative to the floor? Answer in units of J.

What is its gravitational potential energy rel-
ative to a point at the same elevation as the
ball? Answer in units of J.

Homework Equations

PE=mgh

The Attempt at a Solution

I TRIED TO USE THE EQUATION BUT WHEN I PUT IT IN IT WAS WRONG MAYBE I AM CALCULATING WRONG PLEASE HELP MAYBE IF U CAN PROVIDE A MODIFIED EQUATION OR EVEN A SIMPLE ONE THAT WOULD HELP A LOT!

 

[Doc Al]

Homework Equations

PE=mgh

Perhaps if you thought of the equation as PE = mgy, where y is the vertical position with respect to your reference point, you may understand it better.

For example, if you choose the ceiling as your reference, that means that y = 0 at the ceiling. What's the y value of the ball in that case?

 

[Doc Al]

Hint: Pay attention to the sign of your answer.

 

[gansta344u]

thanks a lot it helped a lot especially the last part, it worked.