haruspex's latest activity
-
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... -
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...
-
haruspex replied to the thread Rolling without slipping on a curved surface.I get the same. Curiously, that gives 0 for ##5R=7r##.
-
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...
-
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...
-
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...
-
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...
-
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.
-
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...
-
haruspex replied to the thread Rolling without slipping on a curved surface.Your approach was to take moments about C, but as I have shown that is awkward because you cannot apply the parallel axis theorem...
-
haruspex replied to the thread Rolling without slipping on a curved surface.The parallel axis theorem applies to a rigid body rotating, as a whole, about a given axis. In this problem, the sphere is not doing...
-
haruspex replied to the thread Rolling without slipping on a curved surface.Yes, because in that view all parts of the sphere are rotating about the same axis as a unit. But I think you do have to be careful...
-
haruspex replied to the thread Rolling without slipping on a curved surface.Of course, but it is only of interest in the context of rotation about some axis. It doesn’t have 'a' moment of inertia in that sense...
-
haruspex replied to the thread Rolling without slipping on a curved surface.Your mistake is in applying the parallel axis theorem. That is only valid for a rigid body rotating as a unit about the axis. It would...
-
haruspex replied to the thread Rolling without slipping on a curved surface.Yes, if you take the same sense as positive for both, but no law says you have to. If ##\theta## is the angle clockwise from vertical...