Question

50 circular plates each of radius 7cm and thickness 1/2 cm are placed one above another to form a solid right circular cylinder.find total surface area and volume of cylinder so formed

Answer 1

Solution:-

Since the radius of the cylinder is same as the radius of the circular plate.
So, the radius of the base of the cylinder = 7 cm
Height of the cylinder is same as the thickness of 50 circular plates.
Thickness of 1 plate = 1/2 cm
Then, thickness of 50 plates = 50*1/2
= 25 cm
Height of the cylinder = 25 cm
Total surface area of cylinder = 2πr(r+h)
= 2*22/7*7(7+25)
= 44*32
Total surface area of the cylinder = 1408 sq cm
Volume of the cylinder = πr²h
= 22/7*7*7*25
= 3850 cu cm
Volume of the cylinder is 3850 cu cm
Answer.

Answer 2

Radius of the cylinder=radius of the plate=r=7cm
Height of the cylinder=h= No. of plates × thickness of one plate=50×1/2 =25 cm
∴, total surface area= curved surface area+ 2×area of tha base 
=2πrh+2πr²
=2πr(h+r)
=2×22/7×7(25+7)
=44×32
=1408 cm²
Volume of the cylinder
=πr²h
=22/7×7²×25
=22×7×25
=3850 cm³
∴, total surface area is 1408 cm² and volume is 3850 cm³. Ans.