« first day (2253 days earlier)      last day (46 days later) » 

HNQ
1:44 AM
1
Q: Why is mass a form of energy?

Omer FarooqWhy is mass a very concentrated form of energy? Does it have to do something with photons, phonons or nucleus?

 
 
2 hours later…
HNQ
3:43 AM
4
Q: If all the multipole expansions apart from the monopole is zero, then is the charge density spherically symmetric?

Amit ZachSay I have a charge density $\rho(\vec{x})$ in some finite volume $V$, such that all of the multipole expansions apart from the monopole moment (meaning dipole, quadrupole and so forth) are zero. Does this mean that $\rho(\vec{x})$ is spherically symmetric? I know the opposite is true - meaning, ...

 
 
16 hours later…
HNQ
8:02 PM
3
Q: Why doesn't friction accelerates a ball undergoing rotation?

Noah J. StandersonConsider this situation: The ball is moving forward and undergoing rotation. Assume that it is not slipping. Now eventually the rotation of the ball slows down and the ball eventually comes to a halt. But if you observe the direction of friction (when body is rotating clockwise), you will se...

 

« first day (2253 days earlier)      last day (46 days later) »