posted by Andrea on .
If your last electric bill for sept. was $105. If the average price is 6.5 cents per kw, how many kw did your household use in September?
1kw/.065 = x/$105
is this correct?
How many Joules is that?
I know that 1W =1Joule/second
so 1615.38kw /1000 =1.61538 W
then I get 1.61538W
but how would i get this into joules?
the question is really flawed if you typed it correctly. One pays for energy, not power. The price on an electric bill is for kw-hrs (energy), not per kilowatt.
I don't know what to make of the question at all, especially the second part. Kwatts are not equivalent to joules unless you have time enter into the equation.
You either copied something wrong, omitted an "h" when typing, or your teacher needs a science refresher course. ENERGY is measured in kilowatt-hours (kwh) not kilowatts (kw). POWER is measured in kilowatts. What you pay for is energy, per kwh. Energy is power times time.
Total bill = (no. of kwh) x (cost per kwh, in dollars)
105.00 = N x 0.065
Your answer is numerically correct, but the units are wrong.
To convert kwh to Joules, multiply the number of kwh by this factor:
(3600 Joules/watt-hour)x(1000 watt/kw)
The 3600 comes from the number of seconds in one hour. 1 Joule = 1 Watt-sec