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Q.
Which of the following statements is not correct?
System of Particles and Rotational Motion
Solution:
A rolling body can be imagined to be rotating about an axis passing through the point of contact of the body with the ground. Hence, the instantaneous speed of
the point of contact is zero. Thus, statement (a) is correct.
As the body is rotating, its instantaneous acceleration is not zero. Hence, statement (b) is incorrect.
Once perfect rolling begins, force of friction becomes zero. Hence, work done against friction is zero. Thus, statement (c) is correct.
Rolling cannot take place in the absence of friction because it is the frictional force that provides the necessary torque which makes the body roll on a surface. When the inclined plane is perfectly smooth, the wheel will simply slip under the effect of its weight. Hence, statement (d) is correct.