haruspex's latest activity
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haruspex replied to the thread Problem about units conversion: cm^2 --> m^2.If ##x=y ## then ##x^2=y^2##. If ##10cm=(1/10)m## then what is ##(10cm)^2##? -
haruspex replied to the thread Rolling without slipping on a curved surface.Yes, you do seem to have a sign error in post #59, but where exactly it is depends which sense you are taking as positive for each...
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haruspex replied to the thread Rolling without slipping on a curved surface.If you mean compared with what I posted in post #60, I only meant that your numerator/denominator term reduced to that. I dropped the...
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haruspex replied to the thread Rolling without slipping on a curved surface.Factorise the denominator.
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haruspex replied to the thread Rolling without slipping on a curved surface.Which reduces to ##\frac {5g\sin(\theta)}{7(R-r)}##. Do you know what the answer is supposed to be?
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haruspex replied to the thread Rolling without slipping on a curved surface.Yes.
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haruspex replied to the thread Rolling without slipping on a curved surface.https://en.wikipedia.org/wiki/Moment_of_inertia disagrees. "The moment of inertia, otherwise known as the mass moment of inertia...
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haruspex replied to the thread Rolling without slipping on a curved surface.I would argue strongly against thinking of this "effective MoI" as really being an MoI. MoIs arise usually in three contexts: Angular...
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haruspex replied to the thread Rolling without slipping on a curved surface.I get the same. Curiously, that gives 0 for ##5R=7r##.
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haruspex replied to the thread Rolling without slipping on a curved surface.But I am arguing that you cannot arrive at it using your approach rather than mine because the steps you have to take to find the...
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haruspex replied to the thread Rolling without slipping on a curved surface.I am saying that you cannot apply it to find the moment of inertia of the ball's motion about C. You can apply it, as @kuruman notes...
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haruspex replied to the thread Rolling without slipping on a curved surface.An implication of my previous post is that you should think of moment of inertia as resistance to angular acceleration about the axis...
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haruspex replied to the thread Rolling without slipping on a curved surface.As I wrote in post #28, the moment of inertia of a body is only of interest in the context of rotation about some axis. To put that...
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haruspex replied to the thread Rolling without slipping on a curved surface.We have to assume the sphere has uniform density, so the mass distribution does not change.
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haruspex replied to the thread Rolling without slipping on a curved surface.Yes, but when you say "about axis C" what you mean is that to accelerate it angularly about C at rate ##\alpha## as a rigid body (that...