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Home Q & A Board Science-Related Homework Help High School Level Science
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astuckey astuckey
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5 years ago
A desk top computer plugs into the wall socket at 120V and draws an average current of 2.10 A. How much energy (in kWh) does the computer use each day assuming that it is never turned off?
Show your work, including formulae and substitutions and express your answer rounded correctly and with the appropriate units.
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#1
Educator
5 years ago
One kW = 1000 watts
One hour = 3600 second
One kWh = 1000 * 3500 = 3.6 * 10^6 joules

We will use the following two equations to solve this problem.

Power = Volts * Amps
Energy = Power * time
Power = 120 * 2.10 = 252 watts
This is 252 joules per second.

One day * 24 h/day * 60 min/h* 60 s/h = 8.64 * 10^4 seconds
Energy = 252 * 8.64 * 10^4 = 2.17728 * 10^7 joules.
To convert to kWh, divide by 3.6 * 10^6.
Energy = 2.17728 * 10^7 ÷ 3.6 * 10^6 = 6.048
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