99 Percentile Qs Bank for JEE MainPhysicsLaws of Motion
A half kilogram stone, tied to the end of a string of length 1.0   m , is whirled in a vertical circle with the other end of the string as the centre of the circle. If the angular frequency of the stone is 4   r a d   s - 1 , what is the tension in the string when the stone is at the lowermost position of the circle? (take g = 10   m   s - 2 )
Options
- A3 N
- B5 N
- C8 N
- D13 N
Correct answer
D. 13 N
Step-by-step solution
By the equilibrium of forces, T - m g cosθ = F c T - m g cosθ = m v 2 r T - m g cosθ = m ω 2 r     ∵   v = r ω T l o w e s t = m g + m r ω 2 = 1 2 10 + 1 2 1 4 2 = 5 + 8 = 13 N