3312: Momentum Demonstration

Momentum Demonstration

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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 one of 53 incomplete explanations: This page was created recently. Don't remove this notice too soon. You can help by editing the explanation!

This is a play on a classic lecture demonstration of the conservation of angular momentum, whereby someone holding dumbells with arms extended on a slowly rotating swivel chair brings them closer in to their body, and (by conservation of angular momentum) rotates faster. Beret apparently spins up fast enough in consequence of this to exceed his breakup rotation rate, as would an astronomical object, like 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 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 be gravitationally bound).

Transcript

This is one of 38 incomplete transcripts: Don't remove this notice too soon. You can help by editing the transcript!

[Beret Guy is spinning on a chair, holding two weights away from him. Jill 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 floating outwards, beams blasting out. Jill and Cueball are backing away.]

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

[Beret Guy's chair is now moving, and fire & smoke is spreading around his jet. Jill and Cueball run away]

Jill: 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)
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