Question

A copper and a steel wire of the same diameter are connected end to end. A deforming force F is applied to this composite wire which causes a total elongation of 1 cm. The two wires will have.

• A. The same stress and strain
• B. The same stress but different strain
• C. The same strain but different stress
• D. Different strains and stress

Answer 1

Answer: (B)

The same stress but different strain

Answer 2

: Stress$= \frac{F}{A}$

As each wire is of same diameter, hence the area of cross-section is same for both the wires. As both the wires have the same force (F) and same area of cross-section (1), therefore, stress is same for both the wires.

As young’s modulus,

$Y = \frac{stress}{Strainz}orStrain = \frac{Stress}{Y}$

As Y is different for both the wires and stress is same for both the wires, therefore strains is different for both wires.