An electric motor is a simple rotating machine. Magnets are spaced around a shaft, called the armature. Electromagnets are placed around a cage that surrounds the armature. The cage is called the field windings. When electricity is placed on an electromagnet, it becomes a magnet. When it is removed, it ceases to be a magnet. By timing the electrical pulses, the armature is continuously attracted to the electromagnets in the field windings, causing the shaft to spin.
A windmill is a simple rotating machine driven by the wind. When the wind hits the vanes, it pushes the vanes only one way because the vanes are angled to the wind. Because the vanes are attached to a shaft, the one-way movement is transferred into a circular motion on the shaft. The rotating shaft can be used to drive a generator or to pump water up from a well.
A turbine actually is a windmill inside an enclosed housing, or box. The vanes are replaced by blades, and the wind is replaced by high-pressure steam. When steam hits the angled blades, they can only move one way. Because they are attached to a shaft, the shaft turns, much the same way as a windmill. The rotating shaft is used to drive generators to produce electricity. A jet engine has only one moving part. Turbine blades are attached to a shaft, and the burning fuel creates a strong wind inside the engine.
A water wheel works by using gravity. Buckets are arranged around the rim of a wheel, to catch water. Water from a stream is fed to the top of the wheel, and the weight of the water pulls the buckets down. Because the buckets are attached to the rim, the force turns the central shaft of the wheel. The shaft is then used to drive a generator or a grain-grinding stone.