How do solar sails work if photons don’t have mass?

Question

How do solar sails work if photons don’t have mass?

In: Physics

Answer 1

They don’t have mass, but they do have momentum and energy.

The sail bounces the photon off and conservation of moments takes over.

E^2 = (mc^(2))^2 + (pc)^2

You may be familiar with the case where momentum is 0 (p=0)

E=mc^2

Well, if we take the case where mass is 0 (m=0)

E=pc

The energy of a photon is E=hf (f being frequency and h being planck’s constant)

hf=pc

p=hf/c

c=fλ (λ being wavelength)

So p=h/λ