NTA Abhyas JEE Main2020PhysicsRotational MotionPractice
A solid spherical ball of radius 5 9 m is connected to a point A on the wall with the help of a string which makes an angle θ = 45 ° with the vertical. The sphere can rotate freely about its central axis and it is set into rotational motion against the vertical face of the wall with an angular velocity 100 rad s - 1 . In how much time (in s ) will it come to rest? [ μ = 0 . 1 ]
Correct answer
20
Step-by-step solution
FBD of the spherical ball For translational equilibrium T c o s 45 ° = M g + μ N T sin15° = N Also τ Δ t = Δ L ⇒ μ N R Δ t = I ω 0 Δ t = 2 5 M R 2 ω 0 μ N R Solving we get t = 20 s