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 weight if the metal
weighs 8 g per cm.

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Answer 1

Answer:

Let t is thickness of the cylinder

r

1

is outer radius of the cylinder

r

2

is inner radius of the cylinder

h is height of the cylinder

∴t=2cm

r

1

=14cm

h=70cm

Now, inner radius is calculated as,

r

2

=r

1

−t

∴r

2

=14−2=12cm

1) Volume of the hollow cylinder is given by,

V=c/sarea×heightofcylinder

∴V=(πr

1

2

−πr

2

2

)×h

∴V=π(14

2

−12

2

)×70

∴V=

7

22

(196−144)×70

∴V=22×52×10

∴V=11440cm

3

2) Given wright of the metal, ρ=8

cm

3

g

Let m = mass of the cylinder

∴ρ=

V

m

∴8=

11440

m

∴m=8×11440

∴m=91520gm

∴m=91.520kg