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.
6,009
questions
35
votes
6
answers
18k
views
Is there such thing as a "smallest positive number that isn't zero"? [duplicate]
My brother and I have been discussing whether it would be possible to have a "smallest positive number" or not and we have concluded that it's impossible.
Here's our reasoning: firstly, my brother ...
user361319
33
votes
3
answers
2k
views
What mathematical structure models arithmetic with physical units?
In physics we deal with quantities which have a magnitude and a unit type, such as 4m, 9.8 m/s², and so forth. We might represent these as elements of $\Bbb R\times \Bbb Q^n$ (where there are $n$ ...
- 65.8k
32
votes
2
answers
8k
views
Perfectly centered break of a perfectly aligned pool ball rack
This question is asked on Physics SE and MathOverflow by somebody else. I don't think it belongs there, but rather here (for reasons given there in my comments there; edit: now self-removed).
...
- 3,220
31
votes
0
answers
601
views
Can a 4D spacecraft, with just a single rigid thruster, achieve any rotational velocity?
It seems preposterous at first glance. I just want to be sure. Even in 3D the behaviour of rotating objects can be surprising (see the Dzhanibekov effect); in 4D it could be more surprising.
A 2D or ...
- 5,726
30
votes
5
answers
1k
views
Why does adding a term $5f'(t)$ to $5f''(t)+10f(t)=0$ cause damping?
So we have a differential equation to model an oscillator: $$5f''(t)+10f(t)=0$$
Where the initial conditions are $f(0)=0$ and $f'(0)=4$.
It is given that $f(t) = \frac{2\sqrt 2}{5}\sin\sqrt2 t$.
...
- 1,187
30
votes
2
answers
3k
views
How does one parameterize the surface formed by a *real paper* Möbius strip?
Here is a picture of a Möbius strip, made out of some thick green paper:
I want to know either an explicit parametrization, or a description of a process to find the shape formed by this strip, as it ...
- 27.7k
29
votes
7
answers
10k
views
Does Gödel's Incompleteness Theorem really say anything about the limitations of theoretical physics?
Stephen Hawking believes that Gödel's Incompleteness Theorem makes the search for a 'Theory of Everything' impossible. He reasons that because there exist mathematical results that cannot be proven, ...
- 19.6k
28
votes
3
answers
2k
views
Making a standard theoretical physics argument rigorous
In theoretical physics one often encounters the following rationale:
if $f$ and $g$ are functions on $\mathbf{R}^n$, satisfying some technical conditions, and $\displaystyle\int_\Omega f=\int_\Omega g$...
- 2,014
27
votes
4
answers
6k
views
Why does dust gather in corners?
I've noticed when sweeping the floor that dust gathers particularly in the corners. I assume there is a fluid mechanics reason for this. Does anyone know what it is?
Edit: No, really, this is a ...
- 4,602
27
votes
1
answer
789
views
Density and dimensionality of zeros in inverse square force fields of randomly distributed sources in (at least) 1, 2 and 3 dimensions?
Background: In this answer to Are there places in the Universe without gravity? in Astronomy SE I did a quick finite 2D calculation for 20 random sources to see if there was at least one zero, and ...
- 1,893
25
votes
4
answers
55k
views
What does the integral of position with respect to time mean?
The integral of acceleration with respect to time is velocity.
The integral of velocity with respect to time is position.
What is the integral of position with respect to time, and what does it mean?
...
- 417
25
votes
2
answers
1k
views
Atiyah's definitions of Topological Quantum Field Theory
According to Atiyah, a TQFT is a functor from the category of cobordisms to the category of vector spaces.
How does this definition relate with the physics of quantum mechanics?
What does the ...
- 2,023
24
votes
3
answers
4k
views
Why are harmonic functions called harmonic functions?
Are they related to harmonic series in any way? Or something else? Wikipedia didn't help.
- 4,014
24
votes
2
answers
5k
views
What is the exact and precise definition of an ANGLE?
On wikipedea I found a definition of an Angle as such:
"In order to measure an angle θ, a circular arc centered at the vertex of the angle is drawn, e.g. with a pair of compasses. The length of ...
- 3,989
24
votes
3
answers
2k
views
Calculate moment of inertia of Koch snowflake
That's just a fun question. Please, be creative.
Suppose having a Koch snowflake.
The area inside this curve is having the total mass $M$ and the length of the first iteration is $L$ (a simple ...
- 1,784