Question

The intensity of the Sun's light in the vicinity of the Earth is about 1000W/m^2. Imagine a spacecraft with a mirrored square sail of dimension 5.5 km. Estimate how much thrust (in newtons) this craft will experience due to collisions with the Sun's photons. [Hint: assume the photons bounce off the sail with no change in the magnitude of their momentum.}

Answer 1

Explanation:

Formula to represent thrust is as follows.

             F = $\frac{dP}{dt}$

                = $\frac{2p}{dt}$

or,           p = $\frac{E}{c}$

         $\frac{p}{dt} = \frac{W}{c}$

                  F = $\frac{2IA}{c}$

                     = $\frac{2 (1000 W/m^{2})(5.5 \times 10^{3} m)^{2}}{3 \times 10^{8} m/s}$

                     = 201.67 N

Thus, we can conclude that the thrust is 201.67 N.