The motion of a sphere moving on a rough horizontal surface changes from pure sliding (without rolling) to pure rolling (without slipping). In this process, the force of friction
(`i`) intially acts opposite to the direction of motion and late in the direction of motion
(`ii`) cause linear retardation
(`iii`) causes angular acceleration
(`iv`) stops acting when pure rolling begins

Options

A. initially acts opposite to the direction of motion and later in the direction of motion
B. causes linear retardation
C. causes angular acceleration
D. stops acting when pure rolling begins

Answer

B, C, D

Explanation

`f_(k)` is opposite v it causes linear retardation. But `f_(k)` produces clockwise torque about centre which gives angular acceleration. When pure rolling starts, friction stops acting because bottom point has no tendency to slip.