Rotating Propellers

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Propeller Plane

You need to push backward when you want to move forward. When you're walking down the street, your feet push back against the sidewalk to move you forward. In a car, the wheels do something similar by kicking back against the road. But what about the propellers that power airplanes?

A propeller is a machine that moves you forward through a fluid (a liquid or gas) when you turn it. It has several twisted blades poking out at angles from a central hub, spun around by an engine or motor. Propeller produces lift in a forward direction, a force we refer to as thrust. Its rotary motion through the air creates a difference in air pressure between the front and back surfaces of its blades. This pressure difference pushes the plane forward.

Vacuum Cleaner

The simplest way to explain how a vacuum cleaner can suck up debris is to think of it like a straw. When you take a sip of drink through a straw, the action of sucking creates a negative air pressure inside the straw. A negative air pressure is lower than the pressure of the surrounding atmosphere.

A vacuum cleaner uses an electric motor that spins a fan and creates a region of low pressure inside its pipe, and the outside air pushes dust and dirt into the pipe.