2 ms·

That seems like it would violate the conservation of energy. If all the momentum was linear, than changing the direction of those individual particles would req

That seems like it would violate the conservation of energy. If all the momentum was linear, than changing the direction of those individual particles would require a force.

mwint 4y ago
Lay person’s attempt at an explanation: Centripetal force, but no work is done because the motion of the spinning object is perpendicular to the force continually changing the linear motion to follow the circular course?
uoaei 4y ago
There are forces holding atoms together, such that the conglomerate constitutes a solid object whose geometry is stable in time. Those forces are strong, and are often sufficient to keep a solid object in the same shape even if rotating at high speeds. Sometimes they are not, in which case the solid object is deformed as the individual atoms are "flung outward" by the (ultimately linear) momentum, which overcomes the attractive force that binds atoms into molecules/lattices/whatever.
- derefr 4y ago
  Thought experiment: if you have an elastic band floating in space, and you nudge it repeatedly to get it rotating faster and faster, will it stretch out (the way a timing belt would if run too fast) or will it stay slack? In its own reference frame, is the band being put under tension — and so experiencing elastic deformation — from the momentum of the particles within it?
  - yongjik 4y ago
    Yes it will stretch out.
Schroedingersat 4y ago
Changing linear momentum does require a force (but not necessarily work), as does changing angular momentum. In orbits it's gravity, in particle interactions it's the electromagnetic force.
mlsu 4y ago
Well, if it completes a full rotation, the applied force over the time of the full rotation is zero (hence, work is zero). So yes, the momentum is linear, but it all pencils out by the direction, right? That's my understanding of this, but I'm far from a physics expert.

That seems like it would violate the conservation of energy. If all the momentum was linear, than changing the direction of those individual particles would require a force.

mwint 4y ago

Lay person’s attempt at an explanation: Centripetal force, but no work is done because the motion of the spinning object is perpendicular to the force continually changing the linear motion to follow the circular course?

uoaei 4y ago

There are forces holding atoms together, such that the conglomerate constitutes a solid object whose geometry is stable in time. Those forces are strong, and are often sufficient to keep a solid object in the same shape even if rotating at high speeds. Sometimes they are not, in which case the solid object is deformed as the individual atoms are "flung outward" by the (ultimately linear) momentum, which overcomes the attractive force that binds atoms into molecules/lattices/whatever.

derefr 4y ago
Thought experiment: if you have an elastic band floating in space, and you nudge it repeatedly to get it rotating faster and faster, will it stretch out (the way a timing belt would if run too fast) or will it stay slack? In its own reference frame, is the band being put under tension — and so experiencing elastic deformation — from the momentum of the particles within it?
- yongjik 4y ago
  Yes it will stretch out.

Schroedingersat 4y ago

Changing linear momentum does require a force (but not necessarily work), as does changing angular momentum. In orbits it's gravity, in particle interactions it's the electromagnetic force.

mlsu 4y ago

Well, if it completes a full rotation, the applied force over the time of the full rotation is zero (hence, work is zero). So yes, the momentum is linear, but it all pencils out by the direction, right? That's my understanding of this, but I'm far from a physics expert.