Question

A hollow spherical shell is made of metal of density $4.8$ g/cm${}^3$. If its internal and external radii are $10$ cm and $12$ cm respectively, find the weight of the shell

• A. $15.24$ kg
• B. $12.84$ kg
• C. $14.64$ kg
• D. None of these

Answer 1

Answer: (C)

$14.64$ kg

Volume of spherical shell
$=\frac{4\pi }{3}(R^3-r^3)=\frac{4\pi }{3}({12}^3-{10}^3)$
$=\frac{4}{3}\times \pi \times (12-10)({12}^2+12\times 10+{10}^2)$
$=\frac{4}{3}\times \pi \times 2\times 264c{m}^3$
$Weight=volume\times density=\frac{4}{3}\times \pi \times 364\times 4.8=14.64kg$