IIT JEE , AIEEE Forum - Physics , Mechanics

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The above statement is true only if the cm of the sphere is given some initial velocity, and set in motion over a rough surface. Lets see how:

Initially, the cm of the sphere has some velocity, say, v₀. Then, all points of the sphere have the same velocity, as in translational motion, all points of the rigid body have same velocities.

Hence, the point of contact also has a velocity v₀. hence, the point of contact has a tendency to slip along the direction of v₀, and hence, the maximum value of friction will act to prevent it (its not motion impending, its one that will occur definitely)

Now, this friction is in opposition to v₀ and hence will decrease v₀.

However, it produces a torque and produces a torque that increases the magnitude of angular velocity.

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