Question

20.2 Hollow Cylinder:
Let R be the external radius of a hollow cylinder, r its internal radius and h its
height or length; then
1. Thickness of its wall = R-r
2. Area of cross-section = TR2 - Ter2 = T(R2 - 12)
3. External curved surface = 21Rh
4. Internal curved surface = 2ttrh
5. Total surface area = External curved surface area
+ Internal curved surface area
+ 2 (Area of cross-section)
= 2tRh + 2trh + 21(R2 - 2)
6. Volume of material = External volume - Internal volume
= TR²h - trh
= T(R2 - p2) h.
The area of the curved surface of a cylinder is 4,400 cm2 and the
circumference of its base is 110 cm. Find :
(i) the height of the cylinder,
(ii) the volume of the cylinder.​

Answer 1

Answer:

Given 2πrh = 4400 cm² and 2πr = 110 cm

therefore, 2πrh/2πr = 4400/110 cm

therefore, h = 40 cm

since, 2πr = 110

therefore, r = 110/2π = 110×7/2×22 cm = 35/2 cm

and, volume = 22/7×35/2×35/2×40 cm³

= 38,500 cm³

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Answer 2

Answer:

Given 2πrh = 4400 cm² and 2πr = 110 cm

therefore, 2πrh/2πr = 4400/110 cm

therefore, h = 40 cm

since, 2πr = 110

therefore, r = 110/2π = 110×7/2×22 cm = 35/2 cm

and, volume = 22/7×35/2×35/2×40 cm³

= 38,500 cm³