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Homework Help: Heat Question

  1. Nov 1, 2005 #1
    I've got a question to solve.. Just need 1 thing..

    An automobile cooling system holds 18L of water. How much heat does it absorb if its temperature rises from 20ºC to 90ºC?

    I need to find how many kg of water I have... and then plug into

    Q =mc(T1-T2)

    Q = (m)(4186)(-70)

    Look good? just need help with converting 18L of water into kg\

    Sorry this seems like a school question... I'm just not sure about converting from L to kg.. seemed like general physics to me
    Last edited: Nov 1, 2005
  2. jcsd
  3. Nov 1, 2005 #2


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    Gold Member

    If memory serves me correct, 1 liter of water has a mass of approximately 1 kilogram.

    EDIT: to be more precise, 1 liter weighs 0.96 kilograms.
  4. Nov 1, 2005 #3
    18L*.96 = 17.28kg of water...

    So. Q= (17.28)(4186)(70)
    = 5063385.6J

    I think thats right?
  5. Nov 2, 2005 #4
    Density of Water

    As I understand it, the gram was defined as the mass of 1 cm^3 of water (at 4°C). That would make 1 liter of water exactly 1 kg. Where are you getting the .96 figure?
  6. Nov 2, 2005 #5


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    Gold Member

    Um...I went on wikipedia and did a search on liter

    They said that
    Its that almost exactly thing that made me do s ome searching.
    here is where I got 0.96 from.
    Last edited: Nov 2, 2005
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