Question #53adc

1 Answer
Jul 25, 2015

Negative gravitational potential energy from the reference point of the ground.


Gravitational potential energy is a product of weight and height. Assuming the ground to be defined as height = 0, the bottom of the well has negative height. The product of weight and height (mgh) is negative in this case. Positive work must be done to lift the bucket back to zero potential energy.

one does not have to define the ground as zero, but can choose coordinates and reference frames that suit their problem solving needs. Laws of physics are the same in all frames of reference.
we are ignoring mass energy and thermal energy