Consider a 20 kg uniform circular disk of radius 0.2 m. It is pin supported at its center and is at rest initially. The disk is acted upon by a constant force F= 20 N through a massless string wrapped around its periphery as shown in the figure

Suppose the disk makes n number of revolutions to attain an angular speed of 50 rad `s^(-1).` The value of n, to the nearest integer, is `"_________"`
[Given : In one complete revolution, the disk rotates by 6.28 rad]