What do you call a combination of two or more simple machines?

The correct term for a combination of two or more simple machines is known as a compound machine. In mechanical terms, simple machines include levers, pulleys, inclined planes, wedges, screws, and gears. When these simple machines are integrated or utilized together to perform a particular task, they form a compound machine.

For example, a bicycle is a compound machine because it consists of several simple machines: gears (where the pedals connect to the wheels), wheels and axles, and even levers in the brakes. The efficiency of compound machines arises from the ability to multiply force or change direction, making them pivotal in various mechanical operations.

This concept contrasts with complex machines, which might refer more broadly to intricate systems typically comprising multiple components, both simple and complex. Composite tools and single devices are less commonly used terms in physics and engineering and don’t accurately define the combination of simple machines. Therefore, the term compound machine is most accurate for describing this phenomenon.