Question

A heap of rice is in the form of a cone of diameter $12m$ and height $8m$. Find its volume? How much canvas cloth is required to cover the heap? (use $\pi =3.14$)

Answer 1

Volume of the cone $=\frac{1}{3}\times \pi r^2\times h$

radius $=\frac{12}{2}=6$

height $=8$

$\Rightarrow V=\left(\frac{1}{3}\right)\times 3.14\times 6^2\times 8\Rightarrow V=301.44m^3$

The amount of canvas cloth required is the curved surface area of the heap.

Curved surface area $=\pi \times r\times l$

Now, we know that:

$l^2=r^2+h^2=6^2+8^2=100$

$\therefore l=10m$

Therefore, amount of cloth required $=\pi \times 6\times 10=3.14\times 10\times 6=188.4m^2$