A frame of the reference that is accelerated with respect to an inertial frame of reference is called a non-inertial frame of reference. A coordinate system fixed on a circular disc rotating about a fixed axis with a constant angular velocity $\omega$ is an example of a non-inertial frame of reference. The relationship between the force $\overrightarrow F$ rot experienced by a particle of mass m moving on the rotating disc and the force $\overrightarrow F$ in experienced by the particle in an inertial frame of reference is, $\overrightarrow F$ rot = $\overrightarrow F$ in + 2m ($\overrightarrow v$ rot $\times\overrightarrow \omega$) + m ($\overrightarrow \omega \times\overrightarrow r$) $\times\overrightarrow \omega$, where, vrot is the velocity of the particle in the rotating frame of reference and r is the position vector of the particle with respect to the centre of the disc. Now, consider a smooth slot along a diameter of a disc of radius R rotating counter-clockwise with a constant angular speed $\omega$ about its vertical axis through its centre. We assign a coordinate system with the origin at the centre of the disc, the X-axis along the slot, the Y-axis perpendicular to the slot and the Z-axis along the rotation axis ($\omega$=$\omega\widehat k$). A small block of mass m is gently placed in the slot at r = (R/2) $\widehat i$ at t = 0 and is constrained to move only along the slot. The distance r of the block at time t is