Rotation Ques 2
- A roller is made by joining together two corners at their vertices $O$. It is kept on two rails $A B$ and $C D$ which are placed asymmetrically (see the figure), with its axis perpendicular to $C D$ and its centre $O$ at the centre of line joining $A B$ and $C D$ (see the figure). It is given a light push, so that it starts rolling with its centre $O$ moving parallel to $C D$ in the direction shown. As it moves, the roller will tend to
(2016 Main)
(a) turn left
(b) turn right
(c) go straight
(d) turn left and right alternately
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Answer:
Correct Answer: 2.( a )
Solution:

At distance $x_0$ from $O, v=\omega R$
Distance less than $x_0, v>\omega R$
Initially, there is pure rolling at both the contacts. As the cone moves forward, slipping at $A B$ will start in forward direction, as radius at left contact decreases.
Thus, the cone will start turning towards left. As it moves, further slipping at $C D$ will start in backward direction which will also turn the cone towards left.