A ball of mass (m) 0.5 kg is attached to the end of a string having length (L) 0.5 m. The ball is rotated on a horizontal circular path about vertical axis. The maximum tension that the string can bear is 324 N. The maximum possible value of angular velocity of ball (in radian/s) is
(A)9
(B)18
(C)27
(D)36✓ Correct
Answer: (D)
Solution
For circular motion in a horizontal plane, the horizontal component of tension provides the centripetal force. From the geometry, if the string makes angle θ with vertical, the horizontal radius is r=Lsinθ.
The horizontal component of tension: Tsinθ=mω2r=mω2Lsinθ
This gives: T=mω2L
324=0.5×ω2×0.5
ω2=0.25324=1296
ω=36 rad/s
JEE Advanced · 2011 · 10 Apr 2011 · Paper 1 · Single correct option