rotation

30 ) A

Anirudh can u pls verify my answers for now ???
If it is correct...i'll post the soln.

KYA RE ANIRUDH !!! SUM DE KAR BHAG GAYA KYA ???? {:-(

answer is right
quite an easy one
dx=rw.dt
now integrate

the second one is like hcv example problem
just replaced by groove instead of rod

F X R =12 MR²\alpha

= 12 Ma
F = 12 Ma → a = 2g

v² - u²=2as
u = 0,
v=\omega R
a=2g
S = length of string.
now substitute , we get S = \omega^{2} R^{2}/4g

conserve angular momentum about the centre of rod and it's done.