Which term describes two or more simple machines used together, such as in a bicycle?

• A. Simple Machine
• B. Lever
• C. Pulley
• D. Compound Machine

Answer: (D)

Two or more simple machines working together form a compound machine. A simple machine is a basic device that changes the size or direction of a force, like a lever or a wheel and axle. When several of these basic devices are linked in one system, their combined action makes tasks easier in ways a single simple machine cannot.

A bicycle illustrates this clearly: the pedals and crank act as levers, the wheels and axles let the bike roll, and the gear and chain arrangement transfers motion and adjusts torque and speed. Together, these parts create a single system that uses multiple simple machines to move efficiently, which is the essence of a compound machine.