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Thread: Solar Panel Question??

  1. #1 Solar Panel Question?? 
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    Hi i am currently studying to be a teacher (biology) as part of this training i have to also know a certain amount about physics. I have been given this question as part of a revision excersise i was just wondering if any one could help me out, or at least point me in the right direction.


    A solar panel of area 2 m2 absorbs solar energy at the rate of
    950 W/m2. Assuming that all the energy is used to heat water
    in a 110 litre tank how long would it take for the water
    temperature to increase from 15C to 65C?

    Any help any one could give would be much appreciated


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  3. #2  
    Universal Mind John Galt's Avatar
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    You seem to be missing only a single piece of information to work this problem out. Would you agree?


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  4. #3 Re: Solar Panel Question?? 
    Universal Mind John Galt's Avatar
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    Quote Originally Posted by craig86
    A solar panel of area 2 m2 absorbs solar energy at the rate of
    950 W/m2. Assuming that all the energy is used to heat water
    in a 110 litre tank how long would it take for the water
    temperature to increase from 15C to 65C?

    Any help any one could give would be much appreciated
    We know the panel is absorbing 1900 watts of power.

    We need to know how long it will take to raise the temperature of 110 litres of water by 50 degrees centigrade.

    So we need to know first how much energy it takes to raise one litre of water by one degree centigrade. This is the unknown that I referred to in my first reply. You should be able to locate this in one of your text books, or online. It will probably be quoted in joules. These are units of energy. So if we know how much it takes to raise the temperature of one litre of water by one degree we can easily calculate how much it will take to raise 110 litres by 50 degrees.

    A watt is a measure of the rate of energy production (or use). One watt is one joule per second, so it would now be simple arithmetic(hopefully) to calculate how long it will take to raise the temperature.

    I'm deliberately leaving the detailed working out to you. :wink:

    Let me know if you need any more help.
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  5. #4  
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    The answer I get is 3 hours, 22 minutes.
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  6. #5  
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    i seem to keep coming out with 3 hours 37 miniutes?
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  7. #6  
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  8. #7  
    Forum Ph.D. Wolf's Avatar
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    The answer I get is...

    Oh, look at the time, I've graduated already and don't do homework anymore.

    I'm not doing your problems. Especially if you haven't attempted it yourself. Where's YOUR solution to the problem? What do you think you should do to solve it?

    I'm sure if you post your solution, some of us would be willing to check it out and see what you did right/wrong. Or if yer stuck, please say where and point out what you've done.
    Wolf
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    "Be fair with others, but then keep after them until they're fair with you." Alan Alda
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  9. #8  
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    Quote Originally Posted by Wolf
    Where's YOUR solution to the problem?
    It seems to be here, tough guy!
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  10. #9  
    Forum Ph.D. Wolf's Avatar
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    Too bad he didn't put that in the original post, huh?

    Sorta gives the impression that he wants others to do the work for him.

    Some may like the hand-hold pamper approach, but I prefer the show-your-work approach.

    Whatever.
    Wolf
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    "Be fair with others, but then keep after them until they're fair with you." Alan Alda
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