Recent content by zhangwfjh

F=dp/dt=d(mv)/dt=m(dv/dt)=ma Actually, these two definitions are not equivalent in the framework of special relativity.

In Helmholtz original thesis On integrals of the hydrodynamical equations, which express vortex-motion, he mentioned in the first section that the change undergone by an arbitrary infinitesimal volume of water under the time dt is composed of three different motions. One of them is an expansion...

That can't be possible in special relativity which says the speed cannot exceed speed of light c, irrelevant to the unit of graph

Theorem in electromagnetism says if the divergence \nabla\cdot E and the curl \nabla\times E are known, then E is uniquely determined. So my question is, the divergence equation gives 1 constraint and the curl equation gives 3 constraints, which add up to 4 constraints. On the other hand, the...