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1. A wheel of mass M and radius of gyration "k" spins on a fixed horizontal axle passing through its hub. Assume that the hub rubs the axle of radius "a" at only the top-most point, the coefficient of kinetic friction being μk. The wheel is given an initial angular velocity Wo. Assume uniform deceleration and find (a) the elapsed time and (b) the number of revolutions before the wheel comes to a stop.

2. A solid cylinder of length L and radius R has a weight W. Two cords are wrapped around the cylinder, one near each end, and the cord ends are attached to hooks on the ceiling. The cylinder is held horizontally with the two cords exactly vertical and is then released. Find (a) the tension in each cord as they unwind and (b) the linear acceleration of the cylinder as it falls.

For the first question, I'm not really sure where to start, and we didn't cover radius of gyration. I think if I just get a set up of what information to work with I can get this.

The second one, I drew a FBD and I see that the two tensions will be exerting a torque on the cylinder, but I don't think that the weight gives any torque given where it's acting from - but then I don't know how to incorporate it into getting my answer. I have that 2TR + ?? =I*a/r so far =\

Thanks for any help to get nudge me in the right direction :D

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# Homework Help: Rotational Dynamics Questions (2)

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