Timeline for How to derive moment of inertia for a thin disc?
Current License: CC BY-SA 4.0
17 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Oct 20, 2023 at 1:04 | history | edited | Qmechanic♦ | CC BY-SA 4.0 |
edited tags; edited title
|
| Oct 19, 2023 at 23:16 | history | edited | Gordon | CC BY-SA 4.0 |
Improved formatting for integral
|
| Oct 12, 2023 at 23:07 | comment | added | Gordon | @Ghoster Ok yeah thank you | |
| Oct 12, 2023 at 22:48 | comment | added | Ghoster | No. That integral would give $2\pi r$, which is not the area of a circle. The infinitesimal element of area in polar coordinates is $dA=(dr)(r\,d\theta)=r\,dr\,d\theta$. Notice how it has the proper dimensions to be an area, while your $dr\,d\theta$ does not. | |
| Oct 12, 2023 at 21:06 | comment | added | Gordon | @Ghoster Would the integral setup look like $\int_0^{2\pi}\int_0^r dr d\theta$? | |
| Oct 12, 2023 at 20:11 | comment | added | Gordon | @Ghoster I should try that | |
| Oct 12, 2023 at 20:10 | comment | added | Ghoster | If you’ve never done a 2D integral in polar coordinates, try calculating the area of a circle, by integration, using polar coordinates. | |
| Oct 12, 2023 at 20:10 | comment | added | Gordon | @Ghoster Oh right. I kind of get it now. Thanks | |
| Oct 12, 2023 at 20:07 | comment | added | Ghoster | There are two polar coordinates. That’s the range for $\theta$. It’s not the range for $r$. | |
| Oct 12, 2023 at 19:35 | vote | accept | Gordon | ||
| Oct 12, 2023 at 19:35 | comment | added | Gordon | @Ghoster Would it be 0 to $2\pi$? | |
| Oct 12, 2023 at 19:34 | answer | added | import numpy as np | timeline score: 1 | |
| Oct 12, 2023 at 19:29 | comment | added | Ghoster | What range of polar coordinates describes a thin disk of radius $R$, when the origin is at the center? | |
| Oct 12, 2023 at 19:27 | comment | added | Gordon | @Ghoster Yes, I do | |
| Oct 12, 2023 at 19:25 | comment | added | Ghoster | Do you understand polar coordinates? | |
| S Oct 12, 2023 at 18:12 | review | First questions | |||
| Oct 12, 2023 at 19:10 | |||||
| S Oct 12, 2023 at 18:12 | history | asked | Gordon | CC BY-SA 4.0 |