Engines and Motors
What do a toy car, a blender, a jet plane, a tape recorder, a refrigerator, a lawn mower, a fan, a helicopter, a printing press, an electric drill, and a speeding train all have in common? They contain an engine or motor.
HOW DO ENGINES WORK?
An engine is a machine that makes energy more usable. Engines usually turn heat energy into motion.
Think of a roaring campfire. The fire puts out lots of energy. The fire’s energy may keep you warm, but it won’t take you to soccer practice. An engine can take heat energy and turn it into motion.
The engine in a car, for instance, burns gasoline to make heat. The engine burns the gasoline in small, controlled explosions. These little explosions move parts of the engine up and down. The motion spins a shaft, which is connected to the car’s wheels. When the shaft spins, the wheels turn.
Engines often get hot when they run. They need to be cooled. Most are cooled by air blowing over them. Some use water or other means to take extra heat away.
WHAT POWERS AN ENGINE?
Engines need a source of energy to make them go. Car engines use gasoline, but gasoline is not the only source of energy for engines. Different types of engines use different energy sources. Steam engines use boiling water. Other engines use wood, coal, electricity, or other fuels. The engines turn the energy from these sources into movement.
Engines are sometimes called motors. Some people like to be more specific with the word motor. They only use the term motor to mean engines powered by electricity.
HOW DO ELECTRIC MOTORS WORK?
A motor turns electrical energy into motion. A motor is made from a magnet with a wire wrapped around it. Electricity moving through the wire spins the magnet around!
The spinning magnets are attached to the wheels on a toy car, or the blades of a fan, or whatever the motor is connected to.
The most common motors are called squirrel-cage motors. They look like the wheel a pet hamster might have in its cage for exercise.
TYPES OF ELECTRIC MOTORS
Electric motors use two different types of electricity to run. The kind that flows into your house through the plug on the wall is most likely alternating current, or AC. Most of the motors you use in your house are probably AC motors.
The other type of electricity is called direct current, or DC. DC motors are found many places as well. If you have a toy that runs on batteries, it probably has a DC motor inside.
Some motors are specially designed to run on either type of electricity.
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