At 7.35 cents per kiloway hr, A. what does it cost to operate a 10.0 hp motor for 8.00 hr? B. What does it cost to leave a 75W light burning 24 hr a day?
A. I get a different answer
10 hp = 7460 W = 7.46 kW
Energy used (in kW-h) = 7.46*8 = 59.68
Cost = (59.68 kW-h)*(0.0735 $/kW-h)
= $4.38
A.
1 hp = 0.745699872 kilowatts
10hp X 0.745699872 X 8 = 59.66 kWh
Cost = 59.66 X 0.0735 = R4.38472
B.
75W/1000 X 24 X 0.0735 = R0.1323
To find the cost of operating a motor or leaving a light on, we need to calculate the amount of energy consumed and then multiply it by the cost per kilowatt-hour.
A. To find the cost of operating a 10.0 hp (horsepower) motor for 8.00 hours, we need to convert the horsepower to kilowatts since the cost is given in cents per kilowatt-hour.
To convert horsepower to kilowatts, we can use the following conversion:
1 hp = 0.7457 kW
So, a 10.0 hp motor is equivalent to:
10.0 hp * 0.7457 kW/hp = 7.457 kW
Now, we can calculate the energy consumed by multiplying the power (in kilowatts) by the time (in hours):
Energy consumed = Power * Time
Energy consumed = 7.457 kW * 8.00 hours
To find the cost, we multiply the energy consumed by the cost per kilowatt-hour:
Cost = Energy consumed * Cost per kilowatt-hour
Cost = (7.457 kW * 8.00 hours) * 7.35 cents/kWh
B. To find the cost of leaving a 75W light burning 24 hours a day, we first need to convert the power from watts to kilowatts.
To convert watts to kilowatts, we divide the power by 1000:
75W / 1000 = 0.075 kW
Now, we can calculate the energy consumed by multiplying the power (in kilowatts) by the time (in hours):
Energy consumed = Power * Time
Energy consumed = 0.075 kW * 24 hours
To find the cost, we multiply the energy consumed by the cost per kilowatt-hour:
Cost = Energy consumed * Cost per kilowatt-hour
Cost = (0.075 kW * 24 hours) * 7.35 cents/kWh
By plugging in the numbers and doing the calculations, we can find the answers to both questions.
Just multiply by conversion factors to change from what you have to what you want:
You have
10.0 hp * 8.00 hr = 80.00 hp-hr * 0.0735$/kw-hr = 1088.435 $-hp/kw * 1.0 kw / 1.341 hp = $811.66