An electric heater draws 1100W of power. Electricity costs 8¢ per kW.h. How much does it cost to operate the heater 3h a day for 30 days.
I know the answer is $7.92
Since i need 1100W in to KW.h in order to solve, how would i approach from 1100W (or 1.1kW) to unit of kW.h
2006-11-29 09:07:26 · 6 answers · asked by Anonymous in Science & Mathematics ➔ Physics
kWh is Kilowats/hour - like MPH in a car. kW is Kilowats. Figure out the speed, time and distance formula for the problem and you will have your answer.
2006-11-29 09:10:52 · answer #1 · answered by Richard H 7 · 0⤊ 1⤋
Watts are a unit of power. Energy(J) per unit time (s).
A KW.h is a unit of energy equal to 1000 Watts being produced for 1 hour.
To answer the question, you need to multiply the 1.1kW by the amount of time applied (3h x 30days), then to calculate the cost multiply by the unit cost (8¢).
2006-11-29 09:16:34 · answer #2 · answered by Anonymous · 1⤊ 0⤋
power is equal to the amount of energy produced by an object per unit of time. a kW (kilowatt) is a unit of power equal to 1000 watts, or 1000 joules produced per second.
to go back to energy, multiply the power by the time. a kWh (kilowatt-hour) is a unit of energy equal to 1000 watts being produced over the course of an hour. in standard metric units, 1kWh=1000 W* 1hr* (3600 s/hr)=3.6 million joules. electric companies charge by the kilowatt-hour, so they charge based on the amount of energy used up:
E=1.1 kW(90 h)($ .08/kWh)
=$ 7.92
the amount of time is 90 h since you're operating it for 3 hours over 30 days.
2006-11-29 09:22:10 · answer #3 · answered by Ramesh S 2 · 1⤊ 0⤋
The easiest way to complete these problems is to look at units. To get the units to cancel correctly, you multiply
1.1 kW X total hours X $/kW.h
= 1.1 kW X (3 h/d X 30 d) X .08 $/ kW.h
= 1.1 kW X 90 h X .08 $/kW.h
= $7.92
2006-11-29 09:15:50 · answer #4 · answered by Andrew L 1 · 0⤊ 0⤋
You just take the 1.1kW and multiply the time (in hours) that it was operating.
3hours/day for 30 days = 90 hours. 90 * 1.1kW = 99kW hours
2006-11-29 09:15:46 · answer #5 · answered by xxneo_2000 2 · 0⤊ 0⤋
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2016-10-13 09:21:53 · answer #6 · answered by ? 4 · 0⤊ 0⤋