# Conservation of Angular Momentum is Dumbfounding

• fbs7
In summary, the conversation discusses the concept of conservation of energy and linear momentum, which are relatively easy to understand, but introduces the idea of conservation of angular momentum, which can be tricky to grasp. Two examples are given to explain this concept, one involving a stick with marbles and the other involving a collapsing gas cloud. The conversation also touches on the counterintuitive idea that even when one object is spinning and the other is moving in a straight line, the total angular momentum can still be zero. The experts in the conversation explain that this is because the angular moments of the two objects cancel each other out. The conversation ends with a discussion of the complexity of calculating the behavior of a collapsing gas cloud and how it would not start
Regarding (a), "if I applied no external forces or torques to my system, and now the thing is spinning...", of the original post; sometime before T=1s, the experimenter compressed each of the springs with a required force, thus clearly, an external vector force (torque about the fulcrum) was indeed applied. Then at T=1s, the energy stored in the previously compressed springs were dissipated producing an equal and opposite torque about said fulcrum.

Brendan Graham said:
sometime before T=1s, the experimenter compressed each of the springs with a required force, thus clearly, an external vector force (torque about the fulcrum) was indeed applied.
Nonsense. One can compress a spring by pushing on both ends equally for zero net torque and zero net linear momentum imparted. In any case, the initial conditions for the exercise are what they are and include zero total angular momentum.

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