Chapter 3 Energy 3.1 Energy exists in different forms.
Different forms of energy have different uses. Lamps use electrical energy Plants use energy from the Sun You are using food energy ***Just about everything you see around you involves energy***
Energy Definition - Energy is the ability to cause change. What is energy? Unlike matter, energy is a property of an object. Energy has no mass and no volume.
Forms of Energy 1. Mechanical Energy- Energy you use to move your body. 2. Sound Energy- Energy produced by sound causes particles to vibrate. People can detect these vibrations.
Mechanical Energy
3. Chemical Energy- Energy that is stored in the chemical composition of matter is chemical energy. How much chemical energy there is depends on the type of atoms and how the atoms are arranged. Your energy comes from the chemical energy stored in the foods you eat.
Chemical Energy
4. Thermal Energy- Matter is made of atoms and molecules that are always moving. The energy of the motion in an object is the object’s thermal energy.
Thermal Energy
5. Electromagnetic Energy- This energy is transmitted through space in electromagnetic waves. These waves move through empty space too, they include visible light, x-rays, microwaves. The Sun releases large amounts of electromagnetic energy.
6. Nuclear Energy- The center of an atom, its nucleus, is the source of nuclear energy. A large amount of energy holds the nucleus together. When the nucleus breaks apart or when two small atoms join together, energy is released.
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Kinetic Energy Definition- The energy of motion is called kinetic energy. You must consider the mass of the object and the speed that the object is moving at.
Kinetic Energy increases as the objects mass increases. Example: A soccer ball and a bowling ball The bowling ball has more kinetic energy because it has more mass
Potential Energy Definition- The stored energy that an object has due to its position and its chemical composition. You must consider the source of the potential energy to find how much energy the object has.
The most obvious source of potential energy is from GRAVITY. Another source of potential energy comes from the atoms that the object contains, the CHEMICAL COMPOSITION.
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3.2 Energy can change forms but is never lost
Energy changes forms ExamplesExamples: A match has stored heat and light energy (potential energy). When the potential energy is released chemicals change to heat and light energy.
Energy changes forms Plants convert Energy from the Sun into chemical energy which is stored as sugars in the cells.
Some conversions are obvious Example : light bulbs make light and heat.
Other conversions are useful for everyday needs. Example: Making electricity from running water
Law of Conservation of Energy While kicking a soccer ball the player gives the ball energy and the ball gains an equal amount of that energy. The energy the ball loses is transferred back to the universe as sound or heat energy.
Conversions may produce unwanted forms of energy.
In a fan: The electricity makes the fan blades turn, it also causes heat in the motor of the fan (unwanted/wasted of energy), and it sometimes shakes causing more unwanted wasted energy. If the fan is Energy Efficient it will create more of the desired energy and less unwanted energy.
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