1.

A rod of lengths L is supported two ideal strings of length l such that the system hangs in a vertical plane. Case 1: Rod is kept horizontal displaced slightly perpendicular to the plane and allowed by oscillate. Case 2: Rod is given a small twist about central axis and then allowed to oscillate. Let T_(1), T_(2) be the period of oscillations in the two respective cases.

Answer»

`T_(1)=2pisqrt(l/g)`
`T_(1)=2pisqrt(l/(2g))`
`T_(2)=2pisqrt(l/(6G))`
`T_(2)=2pisqrt(l/(3g))`

Solution :LET `theta` be the angle that the rod rotates about its its central axis and `PHI` be the angle made by string with the VERTICAL.
`-(2Tphi) L/2=(mL^(2))/12 (d^(2)theta)/(dt^(2))`
`IMPLIES(d^(2)theta)/(dt^(2))=-((6g)/L)phi`
or `(d^(2)theta)/(dt^(2))=-((3g)/l)theta`
`impliesT_(2)=2pisqrt(l/(3g))`


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