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    Hello there,
    Have a question: How much heat energy is required to raise the temperature of the water from 20 -80 degrees celsius. Also what's the formula and is there a triangle method to solve problem?. Thankyou.
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    This sounds like part of a larger question where you will be given information such as the mass of the water and the specific heat capacity of the water. And unless there is quite a lot of the question that you haven't told us, there is no need to talk about electricity in the answer at all.

    The equation you need is probably "energy supplied = mass x specific heat capacity x temperature change". If that is the case, then no rearrangement is needed, but when you do have to do this, I would stronly recommend that you try using algebra rather than a triangle method - it is not hard algebra, and with some equations, there is no triangle method that can help you.
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    Sorry yes your right, a bigger question. 300g of water placed in a kettle, temperature increased from 20-80 degree celcius. Heat capacity of water 4180 J Kg-1. So how much heat energy required to raise temp of water 20-80 degrees celcuis. Hope this helps. Thanks
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    I can't think of anything more to say than is in my first post - the way to do it is in there!
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    Checked it out, sorted, thankyou.
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    (Original post by sharan laird)
    Sorry yes your right, a bigger question. 300g of water placed in a kettle, temperature increased from 20-80 degree celcius. Heat capacity of water 4180 J Kg-1. So how much heat energy required to raise temp of water 20-80 degrees celcuis. Hope this helps. Thanks

    The heat capacity of ANY material tells us how much heat energy is needed to raise the temperature of 1kg of that material by 1 celcius.

    In the case of water, we need 4180 Joules to increase 1kg of water by 1 celcius.

    Next we need to know how much water we have which we are told is 300g in other words 0.3kg.

    So to raise 0.3kg of water by 1 celcius, simply multiply the two:

    0.3 x 4180 = ? joules.

    Finally, we need to know how many celcius the temperature rises.

    We are told form 20 to 80 celcius.

    I'm sure you can work out the answer now. What did you get?
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    answer:
    Eh= m*c*temp= 0.3*4180*60=7.5*10 to the power of 4Joules
    A bit messy, couldn't get the superscripts in.
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    (Original post by sharan laird)
    answer:
    Eh= m*c*temp= 0.3*4180*60=7.5*10 to the power of 4Joules
    A bit messy, couldn't get the superscripts in.
    Correct.

    7.524 \rm x 10^4 joules.
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    As for triangle equation (although I agree algebra is better for understanding it fully) they can be useful to get the basic understanding of the equation, for this problem it would be:
    (the energy supplied(j))
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