A coin is placed on a horizontal platform, which undergoes horizontal simple harmonic motion about a mean position O. The coin does not slip on the platform. The force of friction acting on the coin is F.
(i) F is always directed towards O
(ii) F is directed towards O when the coin is moving away from O, and away from O when the coin moves towards O
(iii) `F=0` when the coin and platform come to rest momentarily at the extreme position of the harmonic motion
(iv) F is maximum when the coin and platform come to rest momentarily at the extreme position of the harmonic motion