# Questions tagged [calculus]

Calculus is the branch of mathematics which deals with the study of rate of change of quantities. This is usually divided into differential calculus and integral calculus which are concerned with derivatives and integrals respectively. DO NOT USE THIS TAG just because your question makes use of calculus.

701 questions
Filter by
Sorted by
Tagged with
0answers
25 views

### Degenerate perturbation with the projection operators

I'm studying degenerate perturbation theory in graphene superlattice. The problem is \begin{align} H=H_{0}+\lambda V \end{align} with \begin{align} \mathcal{H}_{0}=&D\begin{pmatrix} 0 &a &...
2answers
33 views

0answers
33 views

### How can I calculate two gases approaching equilibrium over time?

There are two well insulated, rigid tanks (a and b) with known volumes. Each contains a gas with different temperatures, mass, density, specific heat, etc. Gas in tank 'a' has higher pressure than gas ...
0answers
35 views

### Linear harmonic oscillator in quantum mechanics, why we expand the potential into Taylor series?

We have started our first problem in QM by solving Schrödinger equation for the linear harmonic oscillator potential. I noticed that the first thing we did was to expand the potential near the stable ...
1answer
49 views

### How to express the elementary work definition as an explicit functional expression [duplicate]

My assumption here is that in the definition of elementary work : $dW = F ds$ symbol $d$ represents a differential. But a differential implies a function : \$dy =_{df} d[f(x)] = f'(x) \Delta x = f'(...
1answer
27 views

### Barometric formula with variable gravity

Recently, I have wondered about what would be the atmospheric pressure as a function of altitude in a planet that only consists of gas. The equation that does just that is the barometric formula (see ...