Fun Riddles

Question: I'm round at the ends and high in the middle.What am I?

Question: Walk on the living, they don't even mumble.
But walk on the dead, they mutter and grumble.

What are they?

Question: You use me from your head to your toes,
the more I work the thinner I grow.

What am I?

Question: You bury me when I'm alive,
and dig me up only when I die.

What am I?

Question: There are two planes. One is going from New York to London at a speed of 600 MPH. The other is traveling from London to New York at a speed of 500 MPH.

When the planes meet which one will be closer to London?