I'm trying to get the ideal of QCD and it turns out that there seemed to be several versions, and some of which does not appear to agree with each other at a glance. What's the difference, and how does the symmetry come into play? Especially, could you tell me whats the difference between Pert...

Vectors give both magnitude and direction, whereas scalars can be thought of as magnitude without direction. So, velocity is a vector since it is speed with direction. Similarly, what is the scalar analog of acceleration? Velocity is to speed as acceleration is to ______. If there is nothing to ...

There is a question in my textbook. If a massless inextensible string is pulled on with a force of $10 N$, at both ends, what is the tension in the string? It’s a very common question. The answer is $10 N$. It can be proved using Newton’s $2nd$ and $3rd$ law. If we think of the string as a seri...

Is there any difference in the way we perceive two objects, one that reflects white light and another that emits white light?