A stone of mass 1kg is attached to one end of a `1.4 m` long aluminimum wire `0.4 mm` in diameter and stone is rotated in a horizontal plane at a rate such that the wire makes an angle of `60^(@)` with the vertcal. Take Young's modulus of aluminium `= 7 xx 10^(10) N//m^(2)`. If increase in length of the wire is `(2Delta l)/(pi) mm` then value of `Delta l` is :

Answer

5

Explanation

`T' cos theta = mg`
`T' = 2 mg`
So, `Delta l = (T')/(A) (l)/(Y)`