1.

A pendulum made of a uniform wire of cross sectional area A has time period T. When an additional mass M is added to its bob, the time period changes to T_(M) If the Young's modulus of the material of the wire is Y then 1/Y is equal to (g = gravitational acceleration)

Answer»

`[((T_(M))/T)^(2)-1](MG)/A`
`[1-((T_(M)/T)^(2)]A/(Mg)`
`[1-(T/(T_(M))^(2)]A/(M_(g))`
`[((T_(M))/T)^(2)-1]A/(Mg)`

SOLUTION :`T=2pisqrt(l/g)` …(1)
`T_(M)=2pisqrt((l+Deltal)/g)` ..(2)
`Y=(Fl)/(ADeltal)rArrDeltal=(Mgl)/(AY)` ..(3)
`rArr1/Y=A/(Mg)[((T_(M))/T)^(2)-1]`
So correct choice is (d.).


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