jbriggs444's latest activity
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jbriggs444 replied to the thread B Simple mass/scale puzzle.Can you please elaborate for us the broken intuition that you need fixed? Why does your intuition hold that the forces on the two ends... -
You are confusing the 3rd Law with the 2nd Law. Two forces acting on the same piece of string are not a 3rd Law pair. 3rd Law pair...
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jbriggs444 replied to the thread I Problem in understanding instantaneous velocity.The needle has mass and is damped. Undamped needles bounce. A torque that acts on such a needle will not result in an instantaneous...
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jbriggs444 reacted to PeroK's post in the thread I Problem in understanding instantaneous velocity with
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It's not possible. Instantaneous velocity is part of the mathematical model. In Newtonian physics you can postulate that a particle... -
That is part of the pedagogical point of the original scenario, the other part requires a device for measuring that force. I've seen...
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jbriggs444 replied to the thread B Simple mass/scale puzzle.You are looking for the wrong thing. The problem is with your intuition. The way to fix it is to fix the intuition. We already have...
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jbriggs444 replied to the thread B Simple mass/scale puzzle.Units, darn it. 200 N. What would be the effects of this mystical "force" that is everywhere equal to 200 N? The only effects I see...
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Is it? Consider the two configurations 1 and 2 below: Anthropomorphizing the scale, it can only "see" (respond to) what's inside the...
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jbriggs444 replied to the thread B Simple mass/scale puzzle.It is a definition. There is no physical "why". There is only mathematical convenience. It is easier to write ##F_\text{right} = T##...
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jbriggs444 replied to the thread B Simple mass/scale puzzle.I am trying to wrap my head around the intuition you have here. You start with a scale with no weights on either side. It has zero...
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Define it as 20kg then! It won't change the physics. As above, you'll just need to use ##F = T/2## in your free-body diagrams.
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jbriggs444 replied to the thread B Simple mass/scale puzzle.But forces are vectors. That's -100 N on the left and +100 N on the right for a total of 0 N. No surprise there. The rope is not...
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jbriggs444 replied to the thread B Simple mass/scale puzzle.So the [not fully baked] idea is that you sum the magnitude of the force exerted out the one way and the magnitude of the force exerted...
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You could define it as 20kg if you want, but then the force would be given by ##F = T/2##.
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If the spring is stretched to the point where it shows ##10g## on the display, then it provides a ##10g## force at either end. That's...