Timeline for Computing rotational kinetic energy from first principles
Current License: CC BY-SA 4.0
17 events
| when toggle format | what | by | license | comment | |
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| Apr 8 at 1:00 | vote | accept | mzs | ||
| Apr 7 at 14:19 | answer | added | Bob D | timeline score: 0 | |
| Apr 7 at 10:00 | comment | added | Bob D | To facilitate further discussion you really should number all your equations | |
| Apr 6 at 18:50 | comment | added | Bob D | I must admit I didn't follow your derivation, but isn't the last equation what you get after you extracted what you called the "linear kinetic energy"? Which I thought meant what I call the KE of the COM about the axis in your diagram | |
| Apr 6 at 18:30 | comment | added | mzs | @BobD, that should be the right answer. However, the derivation that I showed before seems to be leading to the wrong result, where the rotational kinetic energy is only the component that I would get if the plate was rotating around the axis going through the center of gravity. I am trying to understand where the mistake is. | |
| Apr 6 at 17:35 | comment | added | Bob D | Don’t you think that the rotational KE about your axis is the sum of the rotational KE about an axis parallel to yours through the COM plus the KE of the COM rotating about your axis? | |
| Apr 6 at 16:39 | comment | added | mzs | @BobD I added a sketch that illustrates the situation. Note that the result that I obtained is, in my opinion, wrong because it corresponds to the rotational kinetic energy of a rectangular plate as if it was rotating around an axis going through its center of mass (which is not the case in my situation, as the sketch shows). See for reference the moments of inertia listed here (from which it is easy to recover the rotational kinetic energy). | |
| Apr 6 at 16:31 | history | edited | mzs | CC BY-SA 4.0 |
Added sketch
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| Apr 6 at 16:26 | history | edited | mzs | CC BY-SA 4.0 |
I edit the expression for $T_r$ where I forgot the term $\omega_y^2$
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| Apr 6 at 9:23 | comment | added | Bob D | Doesn’t the result suggest that the total kinetic energy of a rigid body is always the sum of rotational kinetic energy about the center of mass (COM) plus the kinetic energy due to the motion of the COM ? | |
| Apr 6 at 8:51 | comment | added | Bob D | “whose axis of rotation is parallel to the y-axis and goes through the bottom (x,y) face of the plate itself.” Having trouble visualizing where the axis goes through the plate | |
| Apr 6 at 8:06 | review | Close votes | |||
| Apr 6 at 10:12 | |||||
| Apr 6 at 8:00 | history | edited | Qmechanic♦ |
edited tags
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| S Apr 6 at 7:59 | history | suggested | Gabriel Ybarra Marcaida | CC BY-SA 4.0 |
substituted \boldsymbol with \mathbf to properly display it
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| Apr 6 at 7:36 | review | Suggested edits | |||
| S Apr 6 at 7:59 | |||||
| S Apr 6 at 7:24 | review | First questions | |||
| Apr 6 at 7:36 | |||||
| S Apr 6 at 7:24 | history | asked | mzs | CC BY-SA 4.0 |