A steel wire of length 4 m and diameter 5 mm is strethed by 5 kg-wt. Find the increase in its length, if the Young's modulus of steel is `2xx10^(12)` dyne `cm^(2)`

Explanation

Hence, length of the wire, l=4 m =400 cm,
Diameter of wire,2r=5 mm
or radius of wire, r=2.5 mm = 0.25 cm
Force, F kg-wt=5000 g-wt
`5000xx980` dyne
Young's modulus, Y`=2.4xx10^(12)` dyne `cm^(-2)`
As we have `,Y=(F)/(pir^(2))xx(l)/(Deltal)`
Increase in length, `Deltal=(Fl)/(pir^(2)Y)`
`=((5000xx980)xx400)/((22/7)xx(0.25)^(2)xx2.4xx10^(12))=0.0041 cm`