A circular grinding wheel rotates about a fixed axis through its center and slows down with constant angular acceleration. At an initial instant \(t_1\), the wheel rotates with angular speed \(\omega_0\). At a later instant \(t_2\), the wheel rotates with angular speed \(\dfrac{\omega_0}{2}\).

Consider the following three cases:

• Point \(P\) located at distance \(r\) from the axis at instant \(t_1\)
• Point \(Q\) located at distance \(2r\) from the axis at instant \(t_1\)
• Point \(S\) located at distance \(4r\) from the axis at instant \(t_2\)

Which of the following correctly ranks the magnitude of the centripetal acceleration \(a_c\) of the points in these three cases?