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13 Cards in this Set
- Front
- Back
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Energy
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The ability to do work
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Units of Energy
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Joules (J) & Newton-meters
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What does the Law of Conservation of Energy tell us?
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Energy cannot be created or destroyed; in a closed system, total energy remains constant, but it can change forms.
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What is work?
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Force applied over a distance, or force times distance.
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What three conditions must be true for work to occur?
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1. There must be a force
2. There must be displacement 3. The force and displacement must be in the same plane (parallel) |
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Work-Energy Theorem equation
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W = ΔKE
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Work-Energy Theorem equation sentence
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Work is equal to the change of kinetic energy of an object.
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What is mechanical energy? What is it composed of?
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Mechanical Energy is the total energy in a system. IT is composed of potential and kinetic energy.
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How is work done on an object related to GPE?
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The amount of work done to lift an object is equal to the GPE it has at that height.
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As an object falls (neglecting air resistance), what happens to its KE? What happens to its PE?
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The KE increases as the object falls because it speeds up, and the PE decreases as the object falls because its height decreases.
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A boy uses a slingshot to throw a stone into the air. If the stone's initial speed was 3 m/s, and the stone DOES encounter air resistance, how will its final speed compare?
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The speed will be slightly less than 3 m/s.
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12. You prepare to fire a rubber band across the room at a target. If you add 50 J of EPE to the rubber band and no energy is lost to heat or friction, how much KE will the rubber band have when it is released?
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The rubber band will have 50 J of KE once it is released.
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13. Describe power. What are the two units that can be used for power?
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a. POWER IS: work done per unti time, or work divided by time
b. THE UNITS ARE Watts (W) AND Joules/second (J/s) |
