Question

5. What length of solid cylinder 2 cm in diameter must be taken to recast into a hollow cylinder
of external diameter 20 cm, 0.25 cm thick and
15 cm long?​

Answer 1

The length of the cylinder is h = 74.06 m

Step-by-step explanation:

External diameter of hollow cylinder = 20 cm  

Therefore, radius = 10 cm  

Thickness = 0.25 cm  

Internal radius = (10 - 0.25) = 9.75 cm  

Length of cylinder (h) = 15 cm

Volume = πh( R^2 -r^2 ) = π x 15 ( 10^2 - 9.75^2)

             = 15π x 4.93 cm^3

Now diameter of solid cylinder = 2 cm

Radius "r" = 1 cm

Let h be the length

Now volume = πr^2h = π (1 x 1)h  = πh

Now

πh = 15π x 4.93

h = 15 x 4.93

h = 74.06 m

Thus the length of the cylinder is h = 74.06 m

Also learn more

Find the surface area and volume of a sphere whose diameter is 3 cm in terms of Pi ?

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