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• Energy is the ability to do work. • An object that has energy can perform work. • Work is the amount of energy transferred when applying force to What is energy? move something. Therefore, something that has energy can apply a force. • Energy can interact with objects and cause them to move or change. • Energy can also be used to maintain a process or carry out an action.
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• We can classify energy into specific types. Classifying energy this way distinguishes several forms of energy. • There are several specific forms of energy. Six are listed below: 1. Mechanical Energy 2. Light (Radiant) Energy 3. Electrical Energy 4. Sound Energy 5. Thermal Energy 6. Chemical Energy
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• Mechanical energy is energy that an object has due to its motion or position. • Mechanical energy is used to move, lift and hold objects. • A bicycle has mechanical energy because it is moving. • Wind has mechanical energy because it is moving air. • A hammer has mechanical energy because it moves to hammer a nail.
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• Radiant energy is energy that is transferred by electromagnetic waves. • Light usually refers to visible light. Visible light is electromagnetic radiation that is visible to the human eye. • All types of electromagnetic radiation have energy. For this reason, light energy is more accurately called radiant energy. • Infrared, radio waves, UV light, and x‐rays are other types of electromagnetic radiation that have radiant energy.
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• Electrical energy is energy carried by charged particles (electrons). • Electrical energy is also called electricity. • Charged particles can build up on an object. This creates stored electrical energy (static electricity). • Charged particles can move from one place to another. This creates moving electrical energy (current electricity). • Current electricity moves along a path called a circuit. Electrical appliances and devices can harness this energy by hooking up to the circuit.
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• Sound energy is energy carried by sound waves. • Sound waves are longitudinal waves that travel through matter (solid, liquid or gas). • Sound energy is produced when an object vibrates. A vibrating object produces sound, and thus, sound energy. • Unlike light energy, sound cannot travel through a vacuum, because there are no atoms to transmit the vibration.
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• Thermal energy is energy from the movement of particles. • Matter is made of tiny particles called atoms. Atoms are always vibrating. The faster the particles vibrate, the hotter the temperature of the matter. • A hot object has more thermal energy than a cold object. • The amount of thermal energy in a substance has to do with the substance’s temperature as well as the amount of matter in that substance.
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• Chemical energy is energy stored within the bonds between atoms of matter. It is used to keep atoms bonded together. • The bonds between atoms in food and fuel store a lot of chemical energy. • When a person digests food, the bonds break and chemical energy is released. • When fuel is burned, the bonds break and chemical energy is released.
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• Nuclear energy is another form of energy. • Nuclear energy is energy stored within the nucleus of an atom. It is energy that keeps the subatomic particles of the atomic nucleus together. • When an atom splits, its nucleus splits and nuclear energy is released. This process is called nuclear fission. • Nuclear energy can also be released when atomic nuclei combine. This process is called nuclear fusion.
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• Energy can transfer from one object to another. • Energy can also transfer from one location to another. • The movement of energy is called energy transfer. • Energy transfer involves the movement of the same form of energy. The form of energy does not change.
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When a stove warms a pot of water, thermal energy is transferred from the stove to the pot to the water in the pot.
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When a pool stick hits a cue ball to hit the 8 ball, mechanical energy is transferred from the pool stick to the cue ball to the 8 ball.
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Examples of energy transfer from place to place: • Electrical energy produced at power plants transfers via power lines. • Radiant energy from the sun transfer across space to Earth. • Sound energy produced by a radio transfers across a room.
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• Energy cannot be created or destroyed but it can change from one form to another. • Energy transformation is the conversion of energy from one form to another.
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Wind has mechanical energy. A wind mill harvests this energy and transforms it to electrical energy.
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A bouncing ball has mechanical energy. The mechanical energy is transformed to sound energy when the ball bounces on the ground.
BOINK!
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Gasoline has chemical energy. The chemical energy is converted to mechanical energy when a car engine burns the fuel to power the car’s motion.
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How is electrical energy transformed?
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How is electrical energy transformed?
Sound energy (Radio) Light energy (Lamp)
Mechanical energy (Fan) Thermal energy (Toaster)
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• The Law of Conservation of Energy states energy cannot be created or destroyed but it can change form. • When energy is transferred or transformed, it is conserved. This means the total amount of energy stays the same within a system. • A system includes the objects and things around the objects you are studying. • Example: A cue ball hits the 8 pool ball. The system includes the cue ball, the 8 ball, the pool table and surrounding air. Energy 20 20
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Example: A cue ball hits an 8 ball pool ball.
Some energy is transformed into sound BANG! energy. The sound energy is the noise you hear when the cue ball hits the 8 ball. Most energy is transferred from the cue ball to the 8 ball. This energy causes the 8 ball to move.
Some energy is transformed into thermal energy. This energy is absorbed by the table and surrounding air.
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