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How to find power from gallons?

  1. Mar 13, 2013 #1
    during the seven months of the cold season in the northeastern United states, a medium-sized house requires about 1.0x10^8 Btu of heat to keep warm. Atypical furnace delivers 1.3x10^5 Btu of heat per gallon of fuel oil.

    a) How many gallons of fuel oil does a house consume during the cold season if it uses 2.2x10^8 Btu of heat?
    I converted 2.2x10^8 by 2.2x10^8/125,000= 1833 gal

    b)what is the average power delivered by the furnace?
    I dont know how to do this
  2. jcsd
  3. Mar 13, 2013 #2

    rude man

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    Where did 25,000 come from? Try a slightly different number.

    power = heat pr unit time. In this case Btu/sec. If the furnace delivers 2.2e8 Btu in 7 months, how many Btu does it deliver in 1 sec.? Then convert Btu to Joules and you get - what?
  4. Mar 13, 2013 #3
    for 1 I put 125000
    12.12 btu per sec =12 787.2769 joules
  5. Mar 13, 2013 #4

    rude man

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    Sorry, I meant where did 125,000 come from?

    12.12 Btu/s is about right (I got 11.96 but never mind that).

    I'll take your word for the no. of J per Btu.
    So if I generate 12 787.2769 J/sec. what's that in units of power?
  6. Mar 13, 2013 #5
    125000 is the conversion factor from Btu to gal.

    12787.27 J/sec is also watts which is power
  7. Mar 13, 2013 #6

    rude man

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    'Fraid not. Btu and gallons are different units of measure. You can't equate them.

    Look again at how many Btu you get from 1 gallon, then look again at how many Btu are consumed in one season ...
    That is correct.
  8. Mar 13, 2013 #7
    thanks a lot !
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