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 cm3.
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
=π(R2−r2)×h
=227×[(14)2−(12)2]×70=22×[196−144]×10=22×52×10=11440 cm3
Weight of 11440 cm3, if metal is 8 g per cm3
=11440×8=91520 g
Therefore the cylinder weighs 91520 g or 91.520 kg