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If 1 cubic cm of cast iron weights 21 gm, then the weight of a cast iron pipe of length 1 m with a bore of 3 cm and in which the thickness of the metal is 1 cm, is ?
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- 21 kg
- 24.2 kg
- 26.4 kg
- 18.6 kg
Correct Option: C
External radius = 2.5 cm,
length = 100 cm
∴ External volume = [π x (2.25)2 x 100] cm2
internal radius = 1.5 cm
∴ internal volume = [π x (1.5)2 x 100]cm3
Volume of metal
= [π x (2.5)2 x 100 - π x (1.5)2 x 100] cm3
= π x 100 x [(2.5)2 - (1.5)2] cm3
= (22/7 x 100 x 4 x 1 x 21/1000) kg
= 26.4 kg.
