Question

the thickness of a hollow metallic cylinder is 2 cm it is 70 cm long with outer radius of 14 cm find the volume of the metal used in making the cylinder assuming that it is open at both the ends also find its way if the metal weighs 8 gram per centimetre cube

Answer 1

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
$= \pi \: h( {R}^{2} - {r}^{2} )$
$= \frac{22}{7} \times 70 \times ( {14}^{2} - {12}^{2} )$
$= 22 \times 10 \times (196 - 144)$

$= 22 \times 10 \times 52$
=11440cm³

Weight of 1cm³=8gm

So weight of 11440cm³=11440x8

=91520gm

=91520/1000

=91.52kg (1kg=1000gm)
This is your ans hope it will help you in case of any doubt comment below

Answer 2

Thicknesses = 2cm
Height = 70cm
Outer radius [R] = 14cm
Inner radius [r] = Outer radius - thickness
= 14 - 2
=12cm
_____________________________
Volume = pi* [R^2 - r^2]H
= 22/7 [14^2 - 12^2]70
= 22[196 - 144] 10
= 11440cm^3
Weight = Volume * Density
= 11440 * 8
= 91520g
= 91520/1000kg
= 91.52 kg
______________________________
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