Which of the following is NOT a type of simple machine?

A motor is not classified as a simple machine because it does not perform work using a mechanical advantage or a straightforward physical action like the others listed—the lever, screw, and pulley. Simple machines consist of basic mechanical devices that help make work easier by changing the direction or magnitude of a force.

A lever operates on the principle of a fulcrum and helps to lift or move heavy loads with less effort. A screw converts rotational motion into linear motion, enabling the fastening of materials by converting distance moved into force applied. A pulley uses a wheel and rope system to lift loads and can change the direction of force applied. These machines rely on basic mechanics to achieve their functions, while a motor is a complex device that usually converts electrical energy into mechanical energy, involving additional components such as electromagnetic fields and coils, thus exceeding the simple machine definition.