Question

How much iron is needed to make a rod of diameter 1.4 cm and length 30 cm?​

Answer 1

Step-by-step explanation:

Total length=30 cm

Diameter=1.4 cm

Radius=1/2× Diameter

=1/2×1.4

=0.7 cm

Total iron required= Volume of cylinder

=πr^2h

=22/7×0.7×0.7×30

=46.2 cm^3

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Answer 2

Given :

• Length of rod, l = 30 cm
• Diameter of rod, d = 1.4cm
• Radius of rod, r = d/2 = 1.4/2 = 0.7cm

To Find :

• Iron needed to make a rod.

Solution :

We have, r = 0.7 , l = 30

Volume of rod = πr²l

= 22/7 × 0.7 × 0.7 × 30

= 22 × 0.1 × 0.7 × 30

= 22 × 0.7 × 3

= 66 × 0.7

= 46.2cm³

Thus, 46.2cm³ iron is needed to make a rod of diameter 1.4 cm and length 30 cm.

→ Additional information :

• 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)