Rotational MotionHard
Question
Three spools A, B and C are placed on rough ground and acted by equal force F. Then which of the following statement is incorrect?


Options
A.Frictional force on spool A is in backward direction
B.Frictional force on spool B is in backward direction
C.Frictional force on spool C is in backward direction
D.Frictional force on spool C is in forward direction
Solution
For spool A, sliding tendency of point of contact is forward ⇒ frictional force is in backward direction
For spool B, sliding tendency of point of contact is forward ⇒ frictional force is in backward direction
For spool C, sliding 7g tendency of point of contact is forward as without friction

Here a > αR so acceleration of point of contact will be in forward direction.
⇒ frictional force is in backward direction.
For spool B, sliding tendency of point of contact is forward ⇒ frictional force is in backward direction
For spool C, sliding 7g tendency of point of contact is forward as without friction
Here a > αR so acceleration of point of contact will be in forward direction.
⇒ frictional force is in backward direction.
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