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Homework Help: Radiation problem

  1. Sep 19, 2015 #1
    1. The problem statement, all variables and given/known data
    We have a sensor onboard a satellite that is faced towards Earth, from the Sun. The LW absorptivity is 0.8 (a_LW) and SW is 0.2 (a_SW).
    I need to find a equation for the temperature as a function of time. Given datas is the Area=0.3 m^2 and Specific Heat of 4 J/K

    2. Relevant equations
    See below.

    3. The attempt at a solution
    I think that I need to calculate the equilibrium temperature, which I did by using T=((a_sw/a_LW)*(Fs/omega))^1/4,
    Fs=solar flux=1368 W/m^2 and omega= Stefan-Boltsmann constant.

    Later, one equation that I have in mind for the temperature as a function of time is:
    m*c*(dT/dt)=A*omega*T^4 , where A= area and m= mass. The sensor might be really small, so the mass m is negligible (?). What should I do now, I'm stuck.

  2. jcsd
  3. Sep 24, 2015 #2
    Have you thought of anything else to help solve the problem?
  4. Sep 24, 2015 #3


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    2017 Award

    Staff: Mentor

    A negligible mass is equivalent to a satellite that is always at its equilibrium temperature .

    You'll have different areas for absorption of sunlight and emission of infrared light, and those areas depend on the orientation of the satellte.
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