science
posted by biniya .
position of a particle in frame s is given by r=(6t^24t)i3t^3j+3k.in another frame s',its position of the same particle is given by r'=(6t^2+2t)i(3t^3+8t)j+3k.what is the magnitude of relative velocity of s' with respect to s if r and r'are measured in metre and t in second.

I do not understand what you mean by a "frame". If is is "the same particle" in both "frames", why is the time dependence of the position vector different?
If you are talking about two different particles following different trajectories, then the problem makes sense. Just take the time derivative of the r'  r vector. 
position of a particle in frame s is given by r=(6t^24t)i3t^3j+3k.in another frame s',its position of the same particle is given by r'=(6t^2+2t)i(3t^3+8t)j+3k.what is the magnitude of relative velocity of s' with respect to s if r and r'are measured in metre and t in second.

I know the question, which you have merely repeated. You have not responded to my comments and suggestions