30 circular plates, each of radius 14 cm and thickness 3 cm
Question:

30 circular plates, each of radius 14 cm and thickness 3 cm are placed one above the another to form a cylindrical solid.
Find

  1. the total surface area.
  2. volume of the cylinder so formed.

Solution:

Given, radius of a circular plate, r = 14 cm

Thickness of a circular plate = 3 cm

Thickness of 30 circular plates = 30 x 3 = 90 cm

Since, 30 circular plates are placed one above the another to form a cylindrical solid. Then, Height of the cylindrical solid, h = Thickness of 30

circular plates = 90 cm

  1. Total surface area of the cylindrical solid so formed
    = 2πr(h+ r)=2 x (22/7) x 14(90+ 14)
    = 44 x 2 x 104 = 9152 cm2
    Hence, the total surface area of the cylindrical solid is 9152 cm2,
  2. Volume of the cylinder so formed = πr2h
    = (22/7) (14)2 x 90 =(22/7) x 14 x 14 x 90
    = 22 x 28 x 90 = 55440 cm3
    Hence, the volume of the cylinder so formed is 55440 cm3.
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