Question

Find the length of $11$ kg copper wire of diameter $0.4$ cm. Given one cubic cm of copper weights $8.4$ gram.

• A. $132$ m
• B. $116$ m
• C. $111.59$ m
• D. $104.17$ m

Answer 1

Answer: (D)

$104.17$ m

Weight of copper wire is $11$ kg

Radius of copper wire is $\left(r\right)$ is $=0.2$ cm

Density of copper wire is $8.4$ gm \cm cube

So, volume of the copper wire $V=\frac{mass}{density}=\frac{11000}{8.4}c{m}^3$

So, $\pi r^{2}l=\frac{11000}{8.4}$

$\Rightarrow l=\frac{11000}{8.4\left(\frac{22}{7}\right(0.04\left)\right)}=10416.66$ cm

$\Rightarrow l=104.17$ m