What is the law (in the U.S.) about using copyrighted music for a documentary you enter in a contest?

Question

Especially, if you know about it, National History Day.

Answer 1

No! No! No!

You cannot use the work of another person to enter a contest, unless you want to be sued. Contact the copyright owner and ask permission to use the material.

Go to copyright.gov
to understand the use of copyrighted material.

Answer 2

You can't, thats why the songs have a copyright. I was told once that old classical music doesn't have a copyright. You can look into that and see if you can swap out what you currently have.