- #1
crazyog
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Homework Statement
A hot water heater is operated by using solar power. If the solar collector has an area of 6 m^2, and the power per unit area delivered by sunlight is 1000 W/m^2, how long in hours will it take to increase the temperature of 1 m^3 of water from 20C to 60C? (1 cal=4.186 J)
Homework Equations
I'm not really sure...
I know that:
power=(sigma)AeT^4
sigma = Stefan -Boltzman constant = 5.6696x10^(-8) W/m^2*K^4
A = surface area
e = emissivity
T = surface temp.
but we weren't given emissivity so i don't think I use this...
maybe mc(Tf-Ti)/P = (change in time)
?? I'm really clueless on what equation to use, please help!