JEE Main2013PhysicsMechanical Properties of SolidsActual
A copper wire of length 1.0 ~m and a steel wire of length 0.5 ~m having equal cross-sectional areas are joined end to end. The composite wire is stretched by a certain load which stretches the copper wire by 1 ~mm . If the Young's modulii of copper and steel are respectively 1.0 10¹¹ Nm ⁻² and 2.0 10¹¹ Nm ⁻² , the total extension of the composite wire is :
Options
- A1.75 ~mm
- B2.0 ~mm
- C1.50 ~mm
- D1.25 ~mm
Correct answer
D. 1.25 ~mm
Step-by-step solution
Y _ c ( L _ c / L _ c )= Y _ s ( L _ s / L _ s ) 1 10¹¹ ( 1 10⁻³ 1 )=2 10¹¹ ( L _ s 0.5 ) L _ s = 0.5 10⁻³ 2 =0.25 ~mm Therefore, total extension of the composite aligned & wire = L _ c + L _ s & =1 ~mm +0.25 ~m =1.25 ~m aligned