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26 Cards in this Set
- Front
- Back
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What is energy?
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The ability to do work (Remember work is exerting a force over a distance to move an object)
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How is energy measured?
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Joules (J)
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What are the five main forms of energy?
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mechanical, heat, chemical, electromagnetic, and nuclear
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What is mechanical energy?
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Energy of motion...if it's moving, it's mechanical energy, including sound energy and blood flow
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What is heat energy?
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Heat energy comes from friction and causes changes in temperature and phase (like melting ice cube)
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What is chemical energy?
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Energy required to bond atoms together. When bonds are broken, energy is released.
Example: fuel, fire, digestion |
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What is electromagnetic energy?
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Moving electric charges
Examples: electric motors, light, x-rays, radio waves, and laser light |
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What is nuclear energy?
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From the nucleus, when it splits, energy is released
Example: sun's energy (fusion is the most concentrated kind) |
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What are the two states of energy called?
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kinetic and potential energy
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What is kinetic energy?
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Energy of motion, objects with more velocity or more mass have greater the kinetic energy than ones with less
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What is the formula for kinetic energy?
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(mass x velocity^2)/2
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What has the greatest effect on kinetic energy?
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Velocity because it's squared in the formula
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What is potential energy?
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Energy of position
Example: a stretched rubber band, wound-up watch, or a brick bing held above the ground |
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Is it true that objects with potential energy have energy stored?
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Yes
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What is an example of potential energy?
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Chemical energy stored in food or the chemical energy stored in coal and oil
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What is Gravitational Potential Energy?
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Potential energy that depends on height
GPE=weight x height |
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What are changes in the forms of energy called?
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Energy conversions
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What is the most common form of energy conversion?
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kinetic to potential or potential to kinetic
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Where does a tossed ball have the maximum potential and kinetic energy?
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Max. potential energy is at the top of the throw and max. kinetic energy just before it hits the ground (kinetic energy decreases as the ball slows down and increases as the ball speeds up)
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Can all forms of energy be converted to other forms?
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Yes
Example: an electric motor changes electromagnetic to mechanical |
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What is the law of conservation of energy?
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Energy can't be created or destroyed by ordinary means. (Energy is conserved)
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What did Einstein show about mass & energy?
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They are related. If mass is destroyed, energy is created & if energy is destroyed, mass is created
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When traveling at faster speeds, do you use more or less energy?
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more energy
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Why must momentum be conserved?
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Because energy is conserved
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What is a force required to do?
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To change the motion of an object. The force changes the energy of the object
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Why is work conserved?
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Because energy is conserved (Some of the energy may be friction, but the total amount of energy is still conserved)
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