Suppose there's a wheel on the ground, radius R, and I'm pulling it with a string connected the top of the wheel with force T.(adsbygoogle = window.adsbygoogle || []).push({});

We know that if we want the wheel to roll, there has to be friction between the ground and the wheel. But at the same time we ignore that friction and say that the only force on the wheel is T, and the torque is:

N = RxT

So why do we require the existence of friction but also sort of ignore it? I know that it's correct I just want to understand why.

Thanks.

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# Rolling and friction

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