132. How does an airbrush work? Can you briefly explain it again.
In an airbrush, slow-moving but high-pressure air from a hose is allowed to pass through a very narrow channel. As the air enters this channel, it speeds up and its pressure drops—it has exchanged its pressure potential energy for kinetic energy. The channel is so narrow and the air moves so quickly through it that the pressure inside the channel drops below atmospheric pressure! There is a tiny pipe that attaches to this channel at right angles and that dips into a bottle of paint. As the pressure inside the channel falls below atmospheric pressure, the atmospheric pressure in the paint bottle pushes the paint toward the channel. The paint begins flowing into the channel and it collides with the high-speed stream of air. The paint is ripped into tiny droplets and these droplets travels through the channel along with the air. As the air emerges from the narrow channel, its pressure rises and it slows down, but it still moves fast enough to carry the paint droplets to the object that's being painted.