How Does Solar Radiation Pressure Affect an Object in Space?

[mithil03]

The question I have is:
Assume a 100 kg reflective load with 1m2 area at a distance of 1 million kilometers from
the surface of the sun. If the sun’s temperature is 6000K and radius is 695,000 km, find
the radiation pressure exerted on the object. Find how far the load would be from its
initial position after 10 days assuming it started at rest.

I went through the internet and found that
p= W (1+p)/c
Where p – pressure
c – speed of light, 3 ·108 m/sec
W – radiation flux (near the Earth ~1400 W/m2, so-called solar constant
p – overall surface reflectance (from 0 to 1)

But i couldn't relate the Flux value for other distances, and Why would they give the Temperature and radius of the sun ?
Help please..

 

[K^2]

Ok, flux drops as 1/R^2, where R is the distance from the sun. So in order to find flux at some distance R, you can take flux at Earth, W_E, and use this formula:

W_R = W_E\frac{R_E^2}{R^2}

Where R_E is distance of Earth from the Sun.

The reason they give temperature and radius of the Sun is because there is another way to find the flux using black body radiation.

W_R = \sigma T^4 \frac{R_S^2}{R^2}

Where T is temperature of the Sun, R_S is radius of the Sun, R is the distance at which you want to find flux, and sigma is Stefan-Boltzman constant:

\sigma = 5.67 \times 10^{-8} W m^{-2} K^{-4}

 

[mithil03]

Thanks a lot K^2. Understood this now. Could you help me with the next part of the problem please..

 

[K^2]

You already have the formula. Force is pressure times area of the reflector. I'm guessing reflectivity is assumed to be close to 1, so your formula reads P = 2*W/c. That's all you need.