A uniform disc is acted by two equal forces of magnitude F. One of them acts tangentially to the disc, while the other acts at the central point of the disc. The friction between the disc surface and the ground surface is nF. If r be the radius of the disc, then what is the value of n?

Correct option is A. 0
Let fr be the friction exerting between the disc surface and the ground surface, then the motion of the disc is described by:
From force equation:
2F - fr = ma ..(1)
From torque equation:
(F + fr)r = Iα
(F + fr)r = (1/2)mr² × (a/r) ..(2)
Here, a is the linear acceleration of the disc.
α is the angular acceleration of the disc.
I is the moment of inertia about the center.
From equations (1) and (2), on solving we get
(fr = 0) as the answer.