an answer to paradox check it please?

Velocities are measured against a frame of reference. So there are no universal value of velocity for any object in motion or stationary. However, there are still consistent laws relating the motions of objects. In newtonian mechanics, for example, the second law of motion F=ma, holds true for any "inertial frame of reference". In one reference, an object may be stationary but at another moving reference (moving at a constant velocity relative to the first frame of reference), the object may appear moving at the opposite velocity of the moving frame. Now suppose that the object in question is 1 kg pulled by a force of 1 N. Its acceleration will be a=F/m = 1 m/s^2. It means that the object will increase velocity by 1 m/s for every 1s. This is true in both frames of reference. The only difference is that in the "stationary" frame, the object has an initial velocity 0, and its velocities at subsequent seconds are 1, 2, 3, and so on; while for the "moving" frame, the object has an initial velocity, say, u, and then increasing to u+1, u+2, u+3, and so on for every subsequent second. The whole point is that, the law of motion deals with force and acceleration. These quantities are unchanged when measured in any inertial reference frame.