Questions
A physical pendulum pivoted at a point executes angular oscillations. Its mass is m, has its centre of mass at distance r from the point of suspension. If its moment of Inertia is I, then its angular frequency is
detailed solution
Correct option is C
For a body executing simple harmonic motion, Restoring torque acting on it after a small displacement θ, about an axis,torque τ=−cθ here c=couple acting; θ is angular displacement We know that this results in angular oscillations which can be also related by the equation torque=τ=Iα ; here I=moment of inertia; α=angular accelerationEquating the above two we get −cθ=IαWhere for angular oscillations α=−ω2θHence −cθ=−Iω2θ Simplifying this c=Iω2 Hence ω=cIFor angular oscillation ω=cI , where ω=2πTRestoring torque acting on a rod after a small displacement θ, about an axis passing through point of contact O with the curved path,τ=−Mgrsinθ=-r×F=force×perpendicular distance , for small angles sinθ≈θTherefore, τ=−cθ=−MgrθHence c=Mgr. Substituting this is (1) we get ω=MgrI .Talk to our academic expert!
Similar Questions
An sphere of moment of inertia 4 kg/m2 passing through the diameter. It is suspended from a steel wire of negligible mass, whose couple per unit twist is 81 Nm/rad. It is allowed to execute small angular oscillations. The angular frequency of oscillation is
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