Question

. If 1 cm of cast iron weighs 21 g, find the weight of a cast iron pipe
of length 1 m with a bore of 3 cm in which the thickness of the metal
is 1 cm.
​

Answer 1

Solution :

We know that,

$\implies$ Radius = Diameter / 2

$\implies$ Radius = 3 / 2

$\implies$ Radius = 1.5 cm

Inner area of the opening:

$\implies$ Area = πr²

$\implies$ Area = π(1.5 cm)² = 2.25π cm²

Area of the outer area of the opening:

$\implies$ Area = πr²

$\implies$ Area = π(1.5 + 1)² = 6.25π cm²

Volume of metal in the pipe:

$\implies$ Volume = (6.25π - 2.25π) x 100

$\implies$ Volume = 400π cm³

Finding the weight:

$\implies$ 1 cm³ = 21 g

$\implies$ 400π cm³ = 21 x 400π = 26.4 kg

Hence,

The weight of a cast iron pipe is 26.4 kg.

__________________

Answered by: Niki Swar, Goa❤️

Answer 2

Mark me brainliest plzzzz.

Inner radius = (32)cm = 1.5 cm.

Outer radius (1.5 + 1) = 2.5 cm.

∴Volume of iron = [π×(2.5)2×100−π×(1.5)2×100]cm3

= 227×100×(2.5)2−(1.5)2]cm3

= (88007)cm3

∴Weight of the pipe = (88007×211000)kg

= 26.4 kg.(ans)