Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Thermodynamics question?

  1. Oct 17, 2011 #1
    1. The problem statement, all variables and given/known data

    In a solar water heater, energy from the Sun is gathered by rooftop collectors, which circulate water through tubes in the collector. The solar radiation enters the collector through a transparent cover and warms the water in the tubes. Assuming that 80% of the incident solar energy gets lost (i.e; it does not go into heating the water), what collector area is necessary to take water from a 200-L tank and raise its temperature from 20 C to 40 C in 1.0 h? The intensity of incident sunlight is 700 W/m^2.


    2. Relevant equations

    Q = mcdelta t

    delta t = iR

    3. The attempt at a solution
     
  2. jcsd
  3. Oct 17, 2011 #2

    SammyS

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper
    Gold Member

    Welcome to PF.

    What have you tried?

    Where are you stuck?
     
  4. Oct 18, 2011 #3
    I've tried applying those formulas and combinations of them. I don't really understand the problem.
     
  5. Oct 18, 2011 #4

    SammyS

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper
    Gold Member

    What is the definition of power?

    How much energy does it take to raise the temperature of 1 kg of H2O by 1°C
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook