Good Riddles

 
Riddle #31 (easy)

Question: What jumps higher than a building?

Riddle #32 (easy)

Question: Why did the hamburger go to the gym?

Riddle #33 (easy)

Question: What is the center of gravity?

Riddle #36 (easy)

Question: When you fall in me your as happy as could be, but you fall into depression when you lose me.

What am I?

Riddle #38 (easy)

Question: The person who buys me doesn't need me, the person who makes me doesn't want me, and the person who uses me can't appreciate me.

What am I?