A man holds a book near a bookcase at the level of bookshelf B. Bookshelf A is above B. Bookshelf C is below B. Joshua is holding a book near shoulder-height. Use the drop-down menus to indicate what happens to the gravitational potential energy of the book if he places it on each shelf.

shelf A

shelf B

shelf C

What the heck don’t understand

First step is to get rid of the square root. remember that a square root is the same as raising to the (1/2) power. see below: multiply exponents per exponent rules to get: remember you subtract exponents from the denominator and add exponents in the numerator so: simplify further: so a is the correct choice. if you don't understand this google exponent rules and it will you understand. look at the image results.