Independence of mass from speed

It is shown that the dependence of mass on speed contradicts the law of conservation of mass in isolated systems. This makes necessary the modification of Newton's 2nd law with the addition along with the mass of a correction factor, which would take into account the nonlinear dependence of the accelerating force on the speed, due to the existence of its limit. The reasons for the apparent increase in mass with speed , which make the concept of the relativistic mass superfluous