Metal Rods: The Physics of Sound Waves

LOCK IN. Hitting a metal rod on the ground turns it into a budget lightsaber

because of standing waves and your hand is the secret weapon. Grab the rod dead center at the balance

point. That's a node, a spot that stays frozen while everything else vibrates.

Your hand basically tells the universe this part doesn't move. Smack the bottom

into the ground. A compression wave rips through the metal at 5,000 meters per second because

metal is built different. The wave shoots up, hits the end, reflects back,

and now the rod's vibrating. Since your hand holds the node, a standing wave

forms. The middle stays still, the ends wiggle like crazy.