the equation mass X velocity = momentum works but my one of my classes we debated about the photon's momentum. photons have 0 mass so should have 0 momentum but its momentum has been shown with new solar sail technology. so to counteract this i have come up with a new theory volume to the power of density X velocity = momentum then i found out in practical application it dosent work so we only applied it to quantum physics. but because density is so small and its margin of error would over take it so its volume X velocity = momentum still the sum total will still be minute but because photons are so numerous they have over a large area enough momentum to push a solar sail. do you agree with me?