JEE Mains Model Paper 22

Let f be the friction on the ring towards right. ”a' its linear acceleration and α the angular acceleration about centre of mass.

Point of contact P is momentarily at rest i.e. ring will rotate about P.
∴ α =

F(2R)

2MR2

=

F

MR

Now F - f = Ma = MRα = F
f = 0