if photons are massless, how can it push something like a light sail, and how can sunlight adds weight to earth?

Question

if photons are massless, how can it push something like a light sail, and how can sunlight adds weight to earth?

In: 2

Answer 1

Photons have no “rest” mass. So in the frame they aren’t moving they have no mass.

But photons do move at the speed of light, hence have energy, and a relativistic mass. But the term relativistic mass isn’t really used much, and people use total energy instead.