what is instantaneous axis of rotation?

Well you have asked the most fundamental topic of rotational motion. That is Instantaneous axix of rotation. N0w what is it? It is the point about which the body makes pure rolling. It is only that point about which we take the relation V=W×R Here R is the instantaneous axix of rotation In case of problems we often see that the body is sliding then there must be a fixed point whosr radious vector is R about which the reelation V=W×R exist and it is not always the Center of Mass. In case of impure rolling the instantaneous axix of rotation varies and try to shift it to the Center of mass of the body to reach the equilibrium as quickly as possible.

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