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Homework Statement
Homework Equations
Cost = rate x energy consumption (kWh)
Energy consumption = power (kW) x total time (hrs)
The Attempt at a Solution
so here are my answers, can someone please verify if these are correct, thanks!
a)
To calculate power:
There are fifteen 100 W lightbulbs, so to calculate the total power, i would do the following:
P = 15 x 100 W = 1500 W = 1.5 kW
To calculate total time:
8 hrs (per day) x 365 days (since the business operates the following for one year) = 2920 hrs
To calculate electrical energy used in kWh:
E = P x t
E = (1.5 kW) x (2920 hrs)
E = 4380 kWh
To calculate total cost:
I already know the rate: 6.4 cents /kWh
cost = rate x total energy consumption (kWh)
cost = (6.4 cents /kWh) x (4380 kWh)
cost = 28032 cents = $280.32
b)
To calculate power:
P = V^2 / R
P = (120 V)^2 / 15 ohms
P = 960 Watts (multiply this by 2, since there are 2 coffee makers)
P = 960 watts x 2
P = 1920 Watts = 1.92 kW
To calculate total time:
total time = 4 hrs (since both are used for two hours each) x 365 days (since the business operates for one year)
total time = 1460 hrs
To calculate energy consumption in kWh:
Energy = power (kW) x total time (hrs)
Energy = (1.92 kW) x (1460 hrs)
Energy = 2803.2 kWh
To calculate total cost:
cost = rate x energy consumption
cost = (6.4 cents/kWh) x (2803.2 kWh)
cost = 17940.48 cents = $179.4048
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