# Questions tagged [physics]

Questions on the mathematics required to solve problems in physics. For questions from the field of mathematical physics use (mathematical-physics) tag instead.

5,811 questions
Filter by
Sorted by
Tagged with
19 views

### Making a Fourier Transform converge

Consider for example the following function \begin{equation} f(x)=(e^x+1)^{ik_1}\,. \end{equation} For $k_1 \in \mathbb{R}$, this is clearly not absolutely integrable and thus its Fourier transform ...
36 views

### Coupled Resonators with sinusoidal coupling

I have two coupled resonators with complex resonance frequencies of $\beta_1$ and $\beta_2$. The coupling between them is varying sinusoidal with time. The time-evolution of their resonant mode field (...
36 views

83 views

### Help with finding N-point functions with some properties

I'm a physicist and I'm working in a problem in general relativity where I end up with N-point functions that have to satisfy equations like this \begin{equation} \Big[\nabla_\mu \nabla^\mu +V(x_1)\...
143 views

### Why is this the method of characteristics?

The following question refers to ref. 1, the equation are numbered alike with a slightly different notation. The author claims to solve a renormalization group (RG) equation - so the context is ...
1 vote
55 views

### Motion of midpoint of elastic band connected by two gears

A mechanical device consists of two circular gears, one of radius 2 centered at (0, −2) and the other of radius 1 centered at (0, 1). The gear of radius 2 rotates clockwise at unit angular velocity (1 ...
37 views

### Optical path of a light ray reflected from two mirrors and into a pinhole camera

I have been staring at this problem for longer than I would like to admit. I am trying to determine the path of a light ray from an object that is reflected from two plane mirrors and into the ...
83 views

### Finding solution without solving differential equation

I was trying to solve a physics problem and the equation I came up with was: $$F-2kx(t)=mx''(t)$$ It is given that $x(0)=0$ and $x'(0)=0$, and my target is to find the extrema values of $x(t)$ Solving ...
24 views

### Hamiltonian, Unitary and Matrices Exponential

Suppose I can write my Hamiltonian as above. $J_x, J_y, J_z$ and $Q$, etc. are operators. It is obvious that I can add the terms as I want: I can add $J_x + J_y + J_z + ...$ or $J_y + J_x + J_z ...$ ...
31 views

32 views

### how to get phase difference between two given functions?

My physics teacher gave a function $y = A\sin(\omega t \pm kx)$ and he gave it a phase shift of $\pi$ and said that the function would become $A\sin(kx \pm \omega t)$. I wanted to verify it myself so ...
1 vote
38 views

24 views

### Vector Method for a Related Rates Question

A standard related related rates question is: A ladder propped aganist a wall is being moved closer. If the distance between the wall and the ladder reduces by reduces by $a$ m/s, find the rate of ...
1 vote
### Where does this factor of $\pi$ come from in the period of small oscillations about equilibrium points?
I am working through some exercises in Arnold's Mathematical Methods of Classical Mechanics book, specifically the second problem on page 20. For context, $T(E)$ is the period of motion along a closed ...