Newton second law: the net force applied to a body produces a proportional acceleration. Lets fly a rocket. Rocket has some kind of propulsion system that is producing force, so the rocket should accelerate to the infinity. However when the speed is closing to the speed of light, the acceleration slows down, despite the force still beeing applied. Am i right ? What is happening to the newton formula? Lets assume that we have reached 99,9999% of c. The force is still beeing aplied, but rocket will not go any faster? When we turn off the propulsion, the rocket will not slow down. So in that moment applying force will not produce any effect ? Am i right ?