jbriggs444's latest activity
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jbriggs444 reacted to haruspex's post in the thread Chain falling out of a horizontal tube onto a table with
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It might help to treat the mouth in more detail. Say it is a smooth quadrant of radius ##r##. We are interested in the limit as... -
jbriggs444 replied to the thread Chain falling out of a horizontal tube onto a table.Let us reverse engineer that equation. It would have been nice to have you provide the justification for your own equations. You are...
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jbriggs444 replied to the thread Can you get pulled under a train?."Wrong Way Peach Fuzz" at your service.
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jbriggs444 replied to the thread Can you get pulled under a train?.But what if one of the carriers is running in reverse? Then two right sides are available.
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jbriggs444 replied to the thread Graduate A single molecule diffusion in ideal gas.Surely the new random velocity is not obtained directly from the Maxwell distribution. The distribution of resulting velocities should...
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jbriggs444 replied to the thread Is it possible for a vertical rod balancing on a table to lose contact by striking the top of the rod?.I just tossed a pen in the air, giving it an end over end spin. The laws of physics did not prevent it.
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jbriggs444 replied to the thread Undergrad The rocket equation, one more time.dx/dt is not positive by definition. It can be either positive or negative. If ##x## is a differentiable and strictly monotone...
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jbriggs444 replied to the thread Undergrad Acceleration on an electric unicycle, how much does the rider have to lean?.I can ride a real unicycle. One cannot spontaneously lean forward. Instead, one pedals slightly back. This moves the contact point...
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jbriggs444 replied to the thread Chain falling out of a horizontal tube onto a table.The "it" in that passage is the tube. The top of the tube exerts a downward force to impart downward momentum to the chain. The right...
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jbriggs444 replied to the thread Chain falling out of a horizontal tube onto a table.A leftward force to bring the chain to a stop horizontally. And a downward force to bring the chain to a matching rate of motion vertically.
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jbriggs444 replied to the thread Chain falling out of a horizontal tube onto a table.The drawing shows the chain descending vertically. Not in some sort of [evolving!] parabola. This implies that the chain is constrained...
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jbriggs444 replied to the thread Collection of Lame Jokes.They just haven't been exposed to an orthogonal instruction set...
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jbriggs444 replied to the thread Undergrad Conservation of angular momentum in the iceskater example.As the skater's hands are pulled in, they trace out a spiral trajectory. A purely radial force has a non-zero component along the...
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jbriggs444 replied to the thread Undergrad Is calling fictitious forces "not real" just about terminology?.I disagree. The equations are about correlation, not causation. It is attractive to imagine ourselves in the driver's seat "causing"...
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jbriggs444 replied to the thread Undergrad Is calling fictitious forces "not real" just about terminology?.This intuition is a non-starter. Energy depends on reference frame. Causality (to the extent that we have a viable definition to go on)...
