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Homework Help: Force due to Solar Radiation and Gravity

  1. Sep 22, 2015 #1
    1. The problem statement, all variables and given/known data
    Consider a small, spherical particle of radius r located in space a distance R = 3.75 × 1011-m from the Sun. Assume the particle has a perfectly absorbing surface and a mass density of ρ = 3.8-g/cm3. Use S = 214 W/m2 as the value of the solar intensity at the location of the particle. Calculate the value of r for which the particle is in equilibrium between the gravitational force and the force exerted by solar radiation. The mass of the Sun is 2.0 × 1030-kg.

    2. Relevant equations

    mass of particle equals mass density/Volume=3800/(4/3*Pi*r2)

    where C=1 due to complete absorption, S equals cross-sectional area (Pi*[rSUP]2[/SUP]), c equals speed of light

    3. The attempt at a solution



    Have I used the right Solar radiation equation?

    Does this look right?
  2. jcsd
  3. Sep 22, 2015 #2


    User Avatar

    Staff: Mentor

    Check that formula. Does mass really get smaller as the volume of the material gets larger?
    Nope. Besides the issue with the mass expression noted above, I don't see where the solar constant S is involved in your calculation.
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