3312: Momentum Demonstration

Momentum Demonstration

|< < Prev #3312 (October 16, 2026)

Title text: "I'm doing really well on the Hertzsprung-Russell academic diagram, which has spectral class on one axis and Rate My Professors rating on the other."

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Explanation

This is a spin on a classic lecture demonstration of the conservation of angular momentum, whereby someone holding dumbbells with arms extended on a slowly rotating swivel chair brings them closer in to their body, and (by conservation of angular momentum) rotates faster. The expectation is that they then hold the dumbbells further out again to slow down.

In this comic, Beret Guy performs the demonstration accordingly beside Cueball and Hairbun. However, he eventually spins up fast enough to exceed his breakup rotation rate, as an astronomical object would. An example of this is a star being formed out of a collapsing spherical cloud of gas. In such astrophysical situations, exciting things happen to that spherical cloud, such as not being a sphere any more (these things tend to form disks instead). Another feature of such accretion disks is that the central protostar emits astrophysical jets along the axis of rotation, which carry angular momentum away and permit the object to continue rotating close to its breakup velocity instead of disintegrating by rotating too fast to stay gravitationally bound. The particles in these jets are very fast-moving, which means both that they're hot and that they have a lot of momentum themselves. This is most likely one of the strange powers of Beret Guy. The upward-going jet pierces the ceiling, causing chunks of it to fall, and the downward-going one both sets the floor on fire and also, presumably via conservation of (linear) momentum, propels Beret Guy upwards. Though the downward-going jet should impart only the same, but opposite, momentum as the upward-going one, the more immediate interaction with and rebound from the the floor may be the prime reason that it propels Beret Guy preferentially upwards against gravity.

The Hertzsprung–Russell diagram shows the relationship between the stars' absolute magnitudes or luminosities and their effective temperatures (colors). The title text suggests there is a (fictional) Hertzsprung–Russell academic diagram showing the relationship between professor's effective temperature and their rating on the Rate My Professors site. What it would mean to 'do well' on this diagram is unclear, since the two factors have little relationship to start with. In the real world, most professors would not be meaningfully differentiated in their temperature, except perhaps in the metaphorical sense ("My professor is so hot"). However, the axial jets shown in the comic imply a much higher effective temperature, especially given the flames visible below Beret Guy's chair.

Transcript

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[Beret Guy is spinning on a chair, holding two weights away from him. Hairbun and Cueball stand watching him.]

Beret Guy: See, when I hold the weights out, I rotate slowly.

[Beret Guy holds the weights closely, and spins faster. Cueball has his hand up as if thinking.]

Beret Guy: But if I pull them in, I spin faster, due to conservation of angular momentum.

[Beret Guy is spinning much faster, and the chair is moving upwards, beams blasting out. Hairbun and Cueball are backing away.]

Beret Guy: Now, to help shed momentum, I form an axial jet!

[Beret Guy's chair continues moving upwards, and fire and smoke are spreading around his jet. Hairbun is covering her eyes and running away, and Cueball is holding his hands out.]

Hairbun: AAAA

Cueball: AAAAA

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Discussion

f1rst! SomebodyElse (talk) 12:21, 16 October 2026 (UTC)

drat! well, fair is fair 73.132.167.116 12:37, 16 October 2026 (UTC)

Relevant: Black hole#Relativistic jets or Astrophysical jet Rps (talk) 12:22, 16 October 2026 (UTC)

Randall seems to be on an astrophysics streak lately! Darthoctopus (talk) 12:27, 16 October 2026 (UTC)

I added the transcript, though it was a bit of a mess as my W key doesn't work properly, which is annoying. GSLikesCats306 (talk) 13:38, 16 October 2026 (UTC)

What about the title text? 188.107.226.22 14:13, 16 October 2026 (UTC)

What about those Jets? 86.22.132.121 16:00, 16 October 2026 (UTC)

Give 'em lasers and toss 'em in with the Sharks and let 'em rumble. The Sharks have lasers already. 64.201.132.210 16:28, 16 October 2026 (UTC)

This looks remotely related to the recent Navier-Stokes Discovery (an initially smooth fluid under an external force can form a shrinking, accelerating, and elongating swirling vortex that reaches infinite velocity in finite time). --134.102.219.31 15:23, 16 October 2026 (UTC)

I think we're missing the double entendre and subsequent pun in the Title Text. "Spectral Class" is a measure of Temperature, but it does so by analyzing the luminosity of a subject. How a teacher's temperature relates to their score is meaningless, but how "Bright" or "Illuminating" they are is a major component of that score. 63.197.119.253 18:20, 16 October 2026 (UTC)

should the character be renamed from Jill to Hairbun? she looks more of an adult, yet Jill is depicted as a child. Hairbun also shares similar hair styles 2607:FB91:141C:F32:714B:D34B:25F1:B8AC 18:28, 16 October 2026 (UTC)

I agree, it should be Hairbun it doesn't look like Jill at all Jill is short, and Jill is a child 107.1.219.44 19:54, 16 October 2026 (UTC)

isn't rate my professor a measure of how hot (physically attractive) that professor is?
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