Question

if 1 cubic cm of cast iron weights 21 grams then find the weight of a cast iron pipe of length 1 metre with a bore of 3 cm and in which thickness of the metal is 1 cm​

Answer 1

Answer:

"Internal radius = 3/2 = 1.5cm

External radius = 1.5 + 1 = 2.5cm

We know that

Volume of cast iron = (π × (2.5)2 × 100 - π × (1.5)2 × 100)

Taking the common terms out

Volume of cast iron = π × 100 × (2.52 – 1.52)

On further calculation

Volume of cast iron = (22/7) × 100 × (6.25 – 2.25)

So we get

Volume of cast iron = (22/7) × 100 × 4 = 1257.142 cm3

It is given that 1cm3 of cast iron weighs 21g

We know that 1kg = 1000g

So the weight of cast iron pipe = 1257.142 × (21/1000) = 26.4kg

Therefore, the weight of cast iron pipe is 26.4kg. "

Answer 2

Step-by-step explanation:

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.