Question

A copper wire of length 0.9 m and cross-sectional area 1.0 mm² is stretched by a load of 1kg. Young's modulus for copper is 1.2 × 10¹¹ N/m² and g = 10m/s². The extension in wire in mm is –

• A. .013
• B. .075
• C. .11
• D. .13

Answer 1

Answer: (B)

.075

Answer 2

Y =$\frac{FL}{A\Delta L}$

\ DL =$\frac{FL}{YA}$=$\frac{1 \times 10 \times 0.9}{1.2 \times 10^{11} \times 10^{- 6}}$= .075 × 10^–3 m

= .075 mm