Fertilizer Content Sensing

Julie B. in the Digital Fabrication class wants to be able to measure fertilization levels in an aquaponics system. A nitrate test is a good way to measure fertilizer content (scientists use them to test for fertilizer runoff into waterways). I searched the web for...

“Why does a clap make a sound?”

When you clap you compress some air rapidly between your hands. It has to go somewhere, so it rushes out from between your hands in a burst of pressure. That burst of pressure spreads out from your hands, and, traveling at the speed of sound in air (of course),...