A hoop is rolling (without slipping) on the ground. Its axle travels at 20 m/s with respect to the ground. There are two angular positions on the rim where the instantaneous speed (with respect to the ground) is 20 m/s. The two angular positions are separated by an angle of A) 30^o. B) 60^o. C) 90^o. D) 120^o. E) 180^o.

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Quizplus · Accepted Answer

When a hoop rolls without slipping, the point on the rim in contact with the ground is momentarily at rest, and the topmost point moves at twice the speed of the axle. The points with the same speed as the axle are symmetrically located on either side of the vertical diameter, separated by 120 degrees.

A Hoop Is Rolling (Without Slipping) on the Ground