Question

Question 91

The thickness of a hollow metallic cylinder is 2 cm. It is 70 cm long with outer radius of 14 cm. Find the volume of the metal used in making the cylinder, assuming that it is open at both the ends. Also, find its weight if the metal weighs 8 g per $c{m}^3$.

Answer 1

The thickness of the hollow metallic cylinder is 2 cm.
Height of the cylinder = 70 cm
Outer radius of the cylinder = 14 cm
Inner radius of the cylinder = 14 - 2 = 12 cm

Volume of the metal used in making the cylinder = Volume of the hollow cylinder
$=\pi (R^2-r^2)\times h$
$=\frac{22}{7}\times \left[\right(14{)}^2-\left(12{)}^2\right]\times 70=22\times [196-144]\times 10=22\times 52\times 10=11440c{m}^3$
Weight of $11440c{m}^3$, if metal is 8 g per $c{m}^3$
$=11440\times 8=91520g$

Therefore the cylinder weighs $91520g$ or $91.520kg$