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During rolling, the force of friction ac...

During rolling, the force of friction acts in the same direction as the direction of motion of the CM of the body.

Text Solution

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(a) False : Frictional force acts opposite to the direction of motion of centre of mass of a body. In the case of rolling, the direction of motion of the centre of mass is backward, hence, frictional force acts in the forward direction.
(b) True : Rolling can be considered as the rotation of a body about an axis passing through the point of contact of the body with the ground. Hence, its instantaneous speed is zero.
(c ) False : Since body is rolling, it has contripetat force and its instantaneous acceleration is non-zero. So it is false.
(d) True : When perfect rolling begins, the frictional force acting at the lowermost point becomes zero. Hence, work done against friction is also zero.
(e) True : The rolling of a body occurs when a frictional force acts between the body and the surface. The frictional force provides the torque necessary for rolling. In the absence of a frictional force, the body steps from the slope under the effect of own weight.
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