Question

If a load of 9 kg 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

The correct option is B

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

Using Hooke's law, we have

$F=kx\Rightarrow k=\frac{F}{x}=\frac{9\times 9.8}{4.5\times {10}^{-3}}=1.96\times {10}^{4}N{m}^{-1}$