Question 1191906
The theorey involved

Stress ={{{( Force/Area)}}}={{{ (mg/area of cross section)}}}= {{{mg/(pi*r^2)}}}


{{{Strain = Change in length/Original length}}}={{{l/L}}}

Load = 6*9.8 N


length = 3.0 m, 

Change in length= 0.60 mm=0.0006 m

radius = 0.75mm= 0.00075m    Area = pi*(0.00075)^2


Stress= {{{6*9.8)/(pi*0.00075)^2}}}

= 1.059*10^7 N/m^2

Stress = {{{3/0.0006) = 2.0*10^(-4)}}}

{{{Youngs modulus = stress/strain}}}