NEET2019PhysicsRotational MotionActual
A solid cylinder of mass 2   k g and radius 4   c m is rotating about its axis at the rate of 3   rpm . The torque required to stop after 2 π revolutions is
Options
- A2 × 10 - 6 N m
- B2 × 10 - 3 N m
- C12 × 10 - 4 N m
- D2 × 10 6 N m
Correct answer
A. 2 × 10 - 6 N m
Step-by-step solution
From rotational kinematic equations, ω f 2 - ω i 2 = 2 α θ 0 2 - 3   2 π 60 2 = 2   α   2 π 2 π α = - 1 800   r a d   s - 2 ∴ Torque required τ = I α = 2 4 × 10 - 2 2 2 × 1 800 = 16 × 10 - 4 800 = 2 × 10 - 6   N   m