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Water heater warms 137 kg water from 20C to 45 C in 16 min. - Heating element resist?

  1. Apr 1, 2009 #1
    1. The problem statement, all variables and given/known data
    A well-insulated electric water heater warms 137 kg of water from 20°C to 45.0°C in 16.0 min. Find the resistance of its heating element, which is connected across 220-V potential difference.


    2. Relevant equations
    R=V/I


    3. The attempt at a solution
    Not sure how to approach this one. Should I refer to a calorimetry approach along with electrical relations? How might I start this one?

    Any help/hints would be greatly appreciated.
     
  2. jcsd
  3. Apr 1, 2009 #2

    CompuChip

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    Re: Water heater warms 137 kg water from 20C to 45 C in 16 min. - Heating element res

    There is also an equation that relates the power to the voltage V and the resistance R.
    On the other hand, you should be able to calculate the power from the given data.
     
  4. Apr 1, 2009 #3
    Re: Water heater warms 137 kg water from 20C to 45 C in 16 min. - Heating element res

    Gotcha. Thanks for the hint. Looks like Q = mc delta T works great for calculating necessary heat to heat the water while v squared over R multiplied by time (in seconds) equals the heat generated by potential and resistance over time.

    I appreciate your time in providing the hint.
     
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