Question

If a load of 9kg is suspended on a wire, the increase in length is 4.5 mm. The force constant of the wire is

• A. $0.49 \times 10^{4}N/m$
• B. $1.96 \times 10^{4}N/m$
• C. $4.9 \times 10^{4}N/m$
• D. $0.196 \times 10^{4}N/m$

Answer 1

Answer: (B)

$1.96 \times 10^{4}N/m$

Answer 2

Force constant $k = \frac{F}{l} = \frac{mg}{l} = \frac{9 \times 9.8}{4.5 \times 10^{- 3}}$ ⇒

$\mathbf{k = 1.96}\mathbf{\times}\mathbf{1}\mathbf{0}^{\mathbf{4}}\mathbf{N/m}$