Question

Since force is dp/dt, the force due to radiation pressure reflected off of a solar sail can be calculated as 2 times the radiative momentum striking the sail per second. In the vicinity of Earth's orbit around the Sun, the energy intensity of sunlight is about 1300 W/m2. What is the approximate magnitude of the pressure on the sail? (For comparison, atmospheric pressure is about 105 N/m2.)

Answer 1

Answer:

8.67×10⁻⁶ N/m²

Explanation:

p = Momentum of a photon

E = Energy of a photon

c = Speed of light

I = Intensity of light

Force = dp/dt

$p=\frac{E}{c}$

$\\\Rightarrow F=\frac{\frac{dE}{dt}}{c}$

As given in question

$F=2\frac{\frac{dE}{dt}}{c}$

Now F/A = Pressure

$P=\frac{2I}{c}\\\Rightarrow P=\frac{2\times 1300}{3\times 10^{8}}\\\Rightarrow P=8.67\times 10^{-6}\ N/m^2$

∴ Magnitude of the pressure on the sail is 8.67×10⁻⁶ N/m²