However special relativity shows that the mass of an object appears to increase as its speed v (relative to the rest frame) increases.

Furthermore, models where a privileged rest frame exists can escape this difficulty due to other mechanisms.

It is also customary to take W to describe the spin projection along the third direction in the rest frame.

The rest mass is only proportional to the total energy in the rest frame of the object.

The diagram is in the rest frame of the garage.

The paradox occurs when the problem is considered in the rest frame of the bar.

This observer will see a different electric field because the charge is moving at velocity v in their rest frame.

So the charge per unit area on the plates is therefore larger than in the rest frame by a factor of:

The field must be uniform both above and below the plate, since it is uniform in its rest frame.

First consider the rest frame of the particle.