What is a screw?

What is a screw?

• A. A wedge used to split wood
• B. A handle on a door
• C. A wheel that rotates around a central axle
• D. Inclined plane wrapped around a pole that can hold things together or lift

Answer: (D)

Recognizing how a screw works as a simple machine is the focus here. A screw is an inclined plane wrapped around a cylinder, so turning it converts rotational motion into linear motion. That helical shape lets the screw pull parts together or lift loads as you rotate it, with the pitch (how far it moves per full turn) and the friction between threads determining how much force you gain and whether it stays tight. Think of a bolt and nut or a jar lid—the threads grip and translate rotation into clamping or lifting action. Other options describe different machines: a wedge is two inclined planes, a door handle operates as a lever, and a wheel around a central axle is a wheel/axle system. So the definition that describes an inclined plane wrapped around a pole that can hold things together or lift best matches what a screw is.

Recognizing how a screw works as a simple machine is the focus here. A screw is an inclined plane wrapped around a cylinder, so turning it converts rotational motion into linear motion. That helical shape lets the screw pull parts together or lift loads as you rotate it, with the pitch (how far it moves per full turn) and the friction between threads determining how much force you gain and whether it stays tight. Think of a bolt and nut or a jar lid—the threads grip and translate rotation into clamping or lifting action. Other options describe different machines: a wedge is two inclined planes, a door handle operates as a lever, and a wheel around a central axle is a wheel/axle system. So the definition that describes an inclined plane wrapped around a pole that can hold things together or lift best matches what a screw is.