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?

-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