If the surfaces are rough, there is more friction. If you rub your hands together quickly, you can feel them heat up. That’s caused by friction. Ice is a slippery, smooth surface. It has less ...

Friction — you can use the corner of a wall ... Following is a transcript of the video. If you take your hand and you go open and close, you can feel the muscles in your forearm contract.

Can friction be eliminated to help people with ALS live more easily? Columnist Dagmar Munn has found ways to say "yes" to ...