Question

a 75-kg refrigerator is located on the 70th floor of a skyscraper (300 meters above the ground) what is the potential energy of the refrigerator

Answer 1

The gravitational potential energy of an object depends on three things. Its mass, its height above the surface of the earth and the pull of gravity (which is assumed to always be 9.8 m/s².

The Formula for finding the GPE is : m x g x h where m = mass, g = gravitational acceleration and h is height from earth's surface. 

Using this formula we can find that :
GPE= 75 x 9.8 x 300 = 220500J (where J is the SI unit for GPE and stands for Joules.

Answer 2

Potential energy = (mass) x (gravity) x (height above the reference)

-- Relative to the 70th floor, on which the refrigerator is standing,

                  PE = (75 kg) x (9.8 m/s²) x (0)  =  0 joules .

-- Relative to the 35th floor, halfway up to where the fridge is standing,

                  PE = (75 kg) x (9.8 m/s²) x (150 m)  =  110,250 joules .

-- Relative to the ground,

                  PE = (75 kg) x (9.8 m/s²) x (300 m)  =  220,500 joules .