jbriggs444's latest activity
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jbriggs444 reacted to A.T.'s post in the thread Problem with pulleys - two fixed and one movable with
Like.
I think I misunderstood this part. You simply say that in the rest frame of the axis of a pulley, both rope segments at that pulley have... -
jbriggs444 replied to the thread B Conservation of kinetic energy in expanding space.In models with an initial singularity, there is no inception event. The singularity is not part of the manifold.
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jbriggs444 replied to the thread When should a beginner programmer learn vims/emacs?.I use vi for one simple reason. It is always there. Drop me into a shell prompt and I can start using vi immediately. If you drop me...
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jbriggs444 replied to the thread Problem with pulleys - two fixed and one movable.In this situation, depending on the value of ##M##, the outer ropes could accelerate up, down or not at all.
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jbriggs444 reacted to weirdoguy's post in the thread B Conservation of kinetic energy in expanding space with Like.
Which in practice means that we see expansion only at a very large scales. Expansion means that distance between non-gravitationally...
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jbriggs444 replied to the thread B Conservation of kinetic energy in expanding space.An atom is not expanding.
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jbriggs444 replied to the thread Problem with pulleys - two fixed and one movable.You may be thinking of a fixed array of pulleys. In that case, the weight on one end moves with an acceleration opposite to the weight...
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jbriggs444 reacted to phinds's post in the thread B Conservation of kinetic energy in expanding space with Like.
No, since energy is not conserved on cosmological scales, is just isn't there anymore.
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jbriggs444 replied to the thread B Conservation of kinetic energy in expanding space.The easy answer is that energy is not conserved in an expanding universe. The law of conservation of energy follows (via Noether's...
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jbriggs444 reacted to Herman Trivilino's post in the thread B Understanding Newton's Third Law and the Net Force on Objects with Like.
FWIW the term action-reaction can imply that the action has some kind of different status than the reaction. As if one precedes the...
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jbriggs444 reacted to Dale's post in the thread B Understanding Newton's Third Law and the Net Force on Objects with Like.
If you push an object then Newton’s 3rd law says there are two forces. One force acts on you and one force acts on the object (and they...
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jbriggs444 replied to the thread A very naive encryption scheme : How would an expert crack it?.This original series of digits. Is it finite? If the original key is finite then one should instead use a cryptographically strong...
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jbriggs444 replied to the thread B Interstellar asteroids.Sure can. I have no reason to be very confident in my numbers. We have ##F = \frac{mv^2}{r} = \frac{Gm^2}{r^2}## where ##F## is the...
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jbriggs444 replied to the thread Problem with pulleys - two fixed and one movable.You have assumed that the left hand mass ##m_1## and the right hand mass ##m_2## accelerate downward at the same rate, ##a##. What if...
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jbriggs444 replied to the thread B Interstellar asteroids.That clarification was in #6: