Energy of acceleration in inertial reference frames?

If the observer can calculate the dynamic mass of the object at each instant, then the force on that mass will yield an appropriate acceleration; I mean F=ma. Of course this is a calculus problem since the mass will continuously change during any acceleration, but that is the idea.

And so from a Newtonian point of view, F=ma does not hold, but from a relativistic point of view it does.

Different observers would agree that f-ma, but not on the actual values of any of those terms.

Even without considering relativistic effects. observers in different reference frames would disagree on energy values. Consider the observer in frame A (what we arbitrarily call stationary) observing an action in frame B moving at uniform velocity vB with respect to frame A. The experimenter in frame B accelerates a mass M from zero velocity (in his frame) to velocity V in the direction of vB. He calculates the energy needed as the difference between initial and final kinetic energy of the mass. In his frame, that is 0,5*M*V². The observer in reference frame A, observing the same action sees the energy difference as 0.5*M*(V + vB)² - 0.5*M*vB² = 0.5*M*(V² + 2*V*vB)

Comparing these

0.5*M*V² is not equal to 0.5*M*(V² + 2*V*vB)

Relativity changes the degree of inequality, since the velocity summation is different.

Sorry to everyone for going off topic here, but I've been looking for Jane for a while. Pardon my interruption...

Jane- you asked a question about a music video a week or so ago, then posted a link to the video. The link is broken. I'm still interested in seeing what is you were talking about. Would you e-mail me the link or the name of the group/song? Or post it here, or whatever. Thanks!

We now continue with your regularly scheduled program...