Download - Power and electrical power
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Power and electrical power
19 April 2023
Keywords: Power, Energy, Weight, Force
ObjectivesUnderstand what power is and be able to calculate it.
HSW: AF5 – Working critically with evidence AF4 – Using investigative approaches
Used before in: lesson 1 – work Will use again in:
PLTS: Team workers – Work collaboratively with others.
Used before in: Science A Will use again in:
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Outcomes
• All students should be able to describe what makes an object powerful or not.
• Most students should be able to define power and use the equation.
• Some students should be able to evaluate practical work and describe how to make it more valid and reliable.
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Powerful cranes
Which is the most powerful crane? Explain why.
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How is power calculated?The power exerted by an object can be calculated using one of two equations:
Time is measured in seconds (s).
Power is measured in watts (W).
Work done is measured in joules (J).
work done
time takenpower =
Remember that work done = energy transferred.
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A lawnmower engine does 10
kJ of work in 10 seconds. What is the power of the engine?
Calculating power question 1
= 1,000 W = 1 kW
power =work done
time
= 10,000 / 10
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A car transfers 12 mJ of energy in 2 minutes. What is the power of the car?
Calculating power question 2
= 100,000 W = 100 kW
= 12,000,000 / 120
power =work done
time =energy transfer
time
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Power, work and time calculations
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Anagrams
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And finally – we find out – who are more powerful – boys or girls?
• Force x distance = energy• Energy/time = power
Boys: Girls:
Force Dist for 1 rep
reps Total dist
work time power Force Dist for 1 rep
reps Total dist
work time power
Skipping
Lifting
Push ups
Analysis: What conclusion can you draw? Evaluation: was the evidence reliable? Explain.
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Energy Gravitational Watts
Heat Power Kinetic
Electrical1 Joule per
secondJoules
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Plenary - Multiple-choice quiz