What defines a compound machine?

A compound machine is defined by its composition, which includes two or more simple machines working together to perform a task. Simple machines, such as levers, pulleys, wedges, screws, inclined planes, and wheels and axles, are the basic building blocks of mechanical systems. When these simple machines are combined, they can create a compound machine that can more efficiently accomplish a specific function.

For example, a bicycle utilizes several simple machines like wheels (wheel and axle), gears (levers), and chains, all working together to enable movement. This synergy allows compound machines to achieve significant mechanical advantages beyond what a single simple machine could provide.

In contrast, other options either limit the definition of machines to specific types or functionalities, or they incorrectly suggest that a compound machine does not require the integration of simpler mechanisms. Thus, the emphasis on the combination of multiple simple machines as the essence of a compound machine makes this definition accurate and applicable in understanding mechanical principles.