physics

posted by Micah

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?

1. Steve

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

2. drwls

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

3. Elvis Rabohale

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

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