Questions: Screws

Question 1

A screw is really which other simple machine wrapped around a rod?

• A. A lever
• B. A pulley
• C. An inclined plane
• D. A wheel and axle

Answer: (C)

A screw's threads are an inclined plane (ramp) that spirals around a central rod.

Question 2

The spiral ridges on a screw are called threads.

• T. True
• F. False

Answer: True

The raised spiral around a screw is called the thread. It is the part that grips material and pulls the screw forward.

Question 3

Name one object besides a metal screw that uses the screw principle.

Model answer: A jar lid (also acceptable: light bulb, spiral staircase, car jack, bolt, corkscrew).

A jar lid has threads that grip the jar's rim, using the same spiral principle as a screw to tighten or loosen.