Does mass change with velocity?
There is sometimes confusion surrounding the subject of mass in relativity. This is because there are two separate uses of the term. Sometimes people say “mass” when they mean “relativistic mass”, mr but at other times they say “mass” when they mean “invariant mass”, m0. These two meanings are not the same. The invariant mass of a particle is independent of its velocity v, whereas relativistic mass increases with velocity and tends to infinity as the velocity approaches the speed of light c. They can be defined as follows, mr = E/c2 m0 = sqrt(E2/c4 – p2/c2) Where E is energy, p is momentum and c is the speed of light in vacuum. The velocity dependent relation between the two is, mr = m0 /sqrt(1 – v2/c2) Of the two, the definition of invariant mass is much preferred over the definition of relativistic mass. These days when physicists talk about mass in their research they always mean invariant mass. The symbol m for invariant mass is used without the suffix 0. Although relativistic mass
