Question

The thickness of a hollow metallic cylinder is 2 cm. It is 42 cm long and
its inner radius is 10 cm. Find the volume of metal required to make the
cylinder, assuming it is open at both the ends.

Answer 1

Answer:

this will help you in doing the answer

Answer 2

Answer:

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Given

Thickness of cylinder =2cm

Length of cylinder (h) =70cm

Outer Radius (R) =14cm

Then inner Radius(r) =outer Radius - thickness

=14-2

=12cm

Volume of hollow cylinder 

= \pi \: h( {R}^{2} - {r}^{2} )=πh(R2−r2) 

= \frac{22}{7} \times 70 \times ( {14}^{2} - {12}^{2} )=722×70×(142−122) 

= 22 \times 10 \times (196 - 144)=22×10×(196−144) 

= 22 \times 10 \times 52=22×10×52 

=11440cm³

Weight of 1cm³=8gm 

So weight of 11440cm³=11440x8

=91520gm

=91520/1000

=91.52kg (1kg=1000gm)