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14 Cards in this Set
- Front
- Back
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What is "Work Done"
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Energy Transferred
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When a __________ moves and object, _________ is transferred and ________________ is done.
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When a force moves and object, energy is transferred and work is done.
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What happens when something moves an object?
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The thing moving the object needs a supply of energy (food, fuel, electricty).
It does work by moving the object and transfers energy into other forms. This can be useful (lifting a load) or waster (heat) |
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What happens when you work against friction?
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energy gets transferred into heat and sound. wasted!!
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What's the formula for work done?
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Work done (J) = Force (N) x Distance Moved (m)
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A tractor tyre is dragged 5m over flat ground with a force of 340N. What is the work done?
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w = f x d
340 x 5 = 1700J |
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What is Power?
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The rate of doing work (how much per second)
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Is power the same and force and energy?
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NO!!!!!
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Is a powerful machine one that exerts a lot of force?
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NO!!! It is one that can transfer a lot of energy in a short period of time
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What is the formula for power?
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The rate of energy transfer/ doing work
power = work done/ time taken |
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A motor tramsfers 4.8kj of useful energy in 2 minutes
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p = W/t
4800/120 = 40W (or 40 J/s) |
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What is power measured in?
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Watts or J/s (Joules per second)
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What does a Watt = in Joules?
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1 joule of energy per second
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So what does power mean
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How much energy per second
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