Question

how much oron is needed to make a rod of length 63 cm and diameter 2.8 cm

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Answer 1

Given :

• Length = 63m
• Diameter = 2.8cm

To Find :

• Iron needed to make a rod

Solution :

First we have to find the radius

⇒ Diameter (d) = 2.8cm

⇒ Radius (r) = Diameter / 2

⇒ Radius (r) = 2.8 / 2

⇒ Radius (r) = 1.4cm

So we have π = 22/7 , r = 1.4cm , h = 63m

By using Formula,

⇒ Volume of the Cylinder = πr²h

⇒ Volume of the rod = πr²h

⇒ Volume of the rod = 22/7 × (1.4)² × 63

⇒ Volume of the rod = 22/7 × 1.4 × 1.4 × 63

⇒ Volume of the rod = 22 × 1.4 × 1.4 × 9

⇒ Volume of the rod = 22 × 1.96 × 9

⇒ Volume of the rod = 43.12 × 9

⇒ Volume of the rod = 388cm³

•°• Hence, 388cm³ of iron needed to make a rod.

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★ Related Formulas :

• Volume of a cuboid = lbh

• Voume of a cube = l³

• Volume of a cylinder = πr²h

• Volume of a cone =1/3 πr²h

• Volume of a sphere = 4/3 πr³

• Volume of a hemisphere = 2/3 πr³

• Volume of a hollow cylinder = π( R²-r² )h

• Volume of a frustrum of cone = 1/3 πh(R²+r²+Rr)

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Answer 2

Given -

• Length of the rod = 63 cm
• Diameter of rod = 2.8 cm

⠀

To find -

• Iron needed to make the rod.

⠀

Solution -

We have length (height) and diameter of rod.

Then,

• Height = 63 cm
• Radius = 1.4 cm

⠀

For the finding the amount of iron needed to make a rod, we have to find the volume of the rod.

$\large{\bf{\longmapsto{\boxed{\pink{Volume = \pi r^2h}}}}}$

⠀

Putting the values

$\tt\dashrightarrow{Volume = \dfrac{22}{7} \times 1.4 \times 1.4 \times 63}$

⠀

$\tt\dashrightarrow{Volume = 22 \times 0.2 \times 1.4 \times 63}$

⠀

$\tt\dashrightarrow{Volume = 4.4 \times 88.2}$

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$\frak\dashrightarrow{\purple{Volume = 388.08\: cm^3}}$

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$\small{\underline{\sf{Thus,\: 388.08\: cm^3\: of\: iron\: needed\: to\: make\: the\: rod.}}}$