Questions
A uniform rod of length L and mass M is pivoted at the centre. Its two ends are attached to two springs of equal spring constants k. The springs are fixed to rigid supports as shown in the figure and the rod is free to oscillate in the horizontal plane. The rod is gently pushed through a small angle θ in one direction and released. The frequency of oscillation is
detailed solution
Correct option is C
The rod will execute angular oscillationsTorque method:Let rod be turned by small angle θ. Extension in each of the springs = Lθ2Force applied by each spring = kLθ2Torque on the system = −2kLθ2L2=kL2θ2 Iα=−kL2θ2⇒ML212α=−kL2θ2 α=−6kMθAngular acceleration is proportional, and directed opposite, to angular displacement. Hence SHM.⇒f=12παθ=12π6kM Energy method:Let θ be angular displacement at a given time, and ω0 be the angular velocity of the rod at that time. So, ω0=dθdt and α=dω0dtEnergy of the oscillating systemE=12kx2+12kx2+12Iω02 , where x is the extension in each spring.But for small extension, x=Lθ2 So, E=212kLθ22+12ML212ω02Energy is constant. So, dEdt=0 ⇒kL242θdθdt+12ML2122ω0dω0dt=0 ⇒k2θ+M12α=0 ⇒α=−6kMθ Angular acceleration is proportional, and directed opposite, to angular displacement. Hence SHM.⇒f=12παθ=12π6kMTalk to our academic expert!
Similar Questions
A disc of radius R and mass M is pivoted at the rim and is set for small oscillations. If simple pendulum has to have the same period as that of the disc, the length of the simple pendulum should be
799 666 8865
support@infinitylearn.com
6th Floor, NCC Building, Durgamma Cheruvu Road, Vittal Rao Nagar, HITEC City, Hyderabad, Telangana 500081.
JEE Mock Tests
JEE study guide
JEE Revision Notes
JEE Important Questions
JEE Sample Papers
JEE Previous Year's Papers
NEET previous year’s papers
NEET important questions
NEET sample papers
NEET revision notes
NEET study guide
NEET mock tests