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Physics
power and work done
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Created by
Izzie-Mai
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Cards (29)
What is the focus of today's video?
Understanding
power
and its
calculations
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How many definitions of power are there?
Two
definitions
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What is the first definition of power?
Rate at which
energy
is
transferred
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What is the equation for power based on energy transferred?
Power = energy transferred /
time
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What is the second definition of power?
Rate
at which
work
is
done
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What is the equation for power based on work done?
Power
= work done /
time
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What does "work done" refer to?
Energy transferred using a
force
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If you push a car down the road, what is the energy referred to as?
Work done
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How is electrical energy transferred from a plug socket to a phone referred to?
Energy
transferred
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What unit is power measured in?
Watts
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What units are energy transferred and work done measured in?
Joules
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What unit is time measured in?
Seconds
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How much energy does the left lamp transfer?
1200
joules
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How long does the left lamp take to transfer energy?
20
seconds
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What is the power of the left lamp?
60
watts
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How much energy does the right lamp transfer?
1500
joules
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How long does the right lamp take to transfer energy?
30 seconds
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What is the power of the right lamp?
50
watts
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Which lamp is more powerful?
The
left
lamp
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How much energy is transferred by an 1100 watt microwave in three minutes?
198,000
joules
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How do you rearrange the energy transferred equation?
Energy transferred =
power
×
time
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How do you convert three minutes to seconds?
180
seconds
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What is the energy transferred when an 1100 watt microwave is on for three minutes?
198
kilojoules
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How much work is done to push a car down the street?
9
kilojoules
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How much time is taken to do the work of pushing the car?
20
seconds
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What is the power used when pushing the car?
450
watts
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What are the key equations for power?
Power =
energy transferred
/ time
Power =
work done
/ time
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What are the differences between energy transferred and work done?
Energy transferred: No
force
or
movement
Work done: Involves force moving an object
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What are the units for power, energy transferred, work done, and time?
Power:
Watts
Energy transferred
:
Joules
Work done
: Joules
Time: Seconds
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