A solid right circular cone of height 60 cm and radius 30 cm is dropped in a right circular cylinder full of water, of height 180 cm and radius 60 cm.
A solid right circular cone of height 60 cm and radius 30 cm is dropped in a right circular cylinder full of water, of height 180 cm and radius 60 cm. Find the volume of water left in the cylinder, in cubic metres.
We have,
height of cone, $h=60 \mathrm{~cm}$,
the base radius of cone, $r=30 \mathrm{~cm}$,
the height of cylinder, $H=180 \mathrm{~cm}$ and
the base radius of the cylinder, $R=60 \mathrm{~cm}$
Now,
Volume of water left in the cylinder = Volume of cylinder-Volume of cone
$=\pi R^{2} H-\frac{1}{3} \pi r^{2} h$
$=\frac{22}{7} \times 60 \times 60 \times 180-\frac{1}{3} \times \frac{22}{7} \times 30 \times 30 \times 60$
$=\frac{22}{7} \times 30 \times 30 \times 60\left(2 \times 2 \times 3-\frac{1}{3}\right)$
$=\frac{22}{7} \times 54000\left(12-\frac{1}{3}\right)$
$=\frac{22}{7} \times 54000 \times \frac{35}{3}$
$=1980000 \mathrm{~cm}^{3}$
$=\frac{1980000}{1000000} \mathrm{~m}^{3}$
$=1.98 \mathrm{~m}^{3}$
So, the volume of water left in the cylinder is 1.98 m3.