haruspex's latest activity
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haruspex replied to the thread Rolling without slipping on a curved surface.My wording was sloppy; I should have said "for accelerating up the slope". AI's rolling equation is ##\alpha r=(R-r)\ddot\theta##. If it... -
haruspex replied to the thread Rolling without slipping on a curved surface.No, ##\Delta s## is greater than that because of the curved surface. Consider e.g. R only marginally greater than r.
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haruspex replied to the thread Rolling without slipping on a curved surface.Did you see post #13?
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haruspex replied to the thread Rolling without slipping on a curved surface.Ok, here’s what is wrong with the AI solution. First, "the CM acceleration is ##(R-r)\ddot\theta##, not ##a##” is wrong in that it is...
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haruspex replied to the thread Rolling without slipping on a curved surface.I have confirmed your result independently. Will try to locate the error in the AI solution, but rightnowI am a passenger on a very...
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haruspex replied to the thread Rolling without slipping on a curved surface.The OP's analysis appears to be independent of the point in the cycle (other than assuming a nonzero magnitude for the frictional force).
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haruspex replied to the thread Rolling without slipping on a curved surface.No, that is only an approximation for small displacements. But you don’t use it in what you posted, and the question as you have...
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haruspex replied to the thread Electromagnetic field theory -- Potential inside a conducting sphere.That it is at a known distance from every charge, no matter how those charges are distributed around the two shells. This means we can...
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haruspex replied to the thread Electromagnetic field theory -- Potential inside a conducting sphere.No, that clearly would not be true. But the charge on the inner shell will rearrange so that the potential is the same everywhere on...
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haruspex reacted to kuruman's post in the thread Struggling to understand the concept of this question (ice cube in water optics question) with
Like.
For future reference: Please provide the full statement of the problem exactly as given to you including any diagrams. If the answer is... -
haruspex replied to the thread Struggling to understand the concept of this question (ice cube in water optics question).Good, but do you now see how to get that answer?
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haruspex replied to the thread Egg Drop Challenge! Need ideas for winning designs.From the perspective of the physics, the key is that the device needs to exert a certain impulse without exceeding some threshold force...
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haruspex replied to the thread Struggling to understand the concept of this question (ice cube in water optics question).But that cannot apply here since it would provide no way to judge distances. Without goggles, a real eye cannot focus because the lens...
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haruspex reacted to Steve4Physics's post in the thread Struggling to understand the concept of this question (ice cube in water optics question) with Like.
It’s possible that there is a mistake with the question’s wording (Post #1) and a mistake in the diagram (Post #9). If the viewer's eye...
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haruspex replied to the thread 2 wires attached to another wire attached to a block.The other cords are not attached to the weight. Each body only "knows" about the forces that act directly on it. The suspended body is...