Question

A 8 kilogram cat is resting on top of a bookshelf that is 2 meters high. What is the cat’s gravitational potential energy relative to the floor?

Answer 1

-ZERO-   No 17.6 pound Earth-bound cat is going to be able to jump to the top of a 6 feet 7 inch bookshelf unassisted!  Someone should call the SPCA on the writer of this textbook question ;-)

Assuming that this overweight cat is content being placed in such a lofty position, your professor probably wants the answer of 156.8 Joules

Mass x  Acceleration of Gravity (on Earth) x elevation = Potential Energy

8 Kg x 9.8 m/s2  x 2 m  = 156.8 J