I know that momentum is a potential to change energy not necessarily involving mass. But, could someone please explain what force is actually imparted? I’m stuck thinking of the sail like a battery that was just given a charge, but has no propulsion system to provide the charge to.
In: Physics
Photons don’t have mass but they do have energy, and Einstein says that mass and energy are the same thing. That means they still have momentum and still impart force in a collision.
This effect isn’t just present on solar sails; if you stand in the sun (or in front of a light bulb, even) the light hitting you is imparting pressure on you, it’s just incredibly miniscule. Some cursory googling tells me the radiation pressure from the sun on Earth is about 10 micropascals, or about one ten-billionth the air pressure at sea level.
Even with such a tiny amount of force solar sails (theoretically) work because in space there’s virtually nothing to slow you down.
Photons don’t have mass, but *do* have momentum (and energy). If one is reflected off a sail, it transfers momentum, same as if you’d thrown a tennis ball that bounced off the sail.
The solar wind isn’t actually light. It’s a mixture of charged electrons, protons and alpha particles (two protons and two neutrons), all of which have mass, although they are very small
Edit: Fixing spelling because the latest update seems to have slightly broken comments and I can’t see what I’m writing
Latest Answers