Question

What length of solid cylinder 2 cm in diameter must be taken to recast into a hollow cylinder of length 15 cm?

Answer 1

Answer:

Here is your answer!

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Given diameter of solid cylinder = 2 cm

Radius of solid cylinder, r = 1 cm

Volume of solid cylinder =  πr2h

= π × 12 × h = πh →  (1)

Length of hollow cylinder, H = 16 cm

External diameter = 20 cm

External radius = 10 cm

Thickness = 2.5 mm = 0.25 cm

Internal radius = 10 – 0.25 = 9.75 cm

Volume of hollow cylinder  = π[102 – (9.75)2] × 16

= 16π × 19.75 × 0.25 →  (2)

From (1) and (2), we get

Πh = 16π × 19.75 × 0.25

  

∴ h = 16 × 19.75 × 0.25 = 79 cm 

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Hope it helps!