Question

The area of cross section of a steel wire is$0.1 \mathrm {~cm} ^ { 2 }$. The force required to double its length will be

• A. $2 \times 10 ^ { 12 } N$
• B. $2 \times 10 ^ { 11 } N$
• C.
• D.

Answer 1

Answer: (D)

Answer 2

When the length of wire is doubled then $l = L$ and strain = 1 ∴ Y = strain =$\frac { F } { A }$

∴ Force = Y × A $= 2 \times 10 ^ { 11 } \times 0.1 \times 10 ^ { - 4 }$