Page 82 - WCS - Electrical

WORKSHOP CALCULATION & SCIENCE - CITS

= (D + d) (D - d) h

Total surface area of hollow cylinder = Inner + outer curved area + area of top and bottom circular part

TSA : 2 Rh + 2 rh + 2 (R² - r²)
R = outer radius
r = inner radius
D = outer diameter

d = inner diameter
h = height of cylinder
t = thickness
D - d
Mean dia =
2
If thickness given then:

Volume of hollow cylinder = p x mean dia x thickness x height
Finding out volumes of solids
The space occupied by a body is known its volume. The volume of a body indicates the capacity to hold substance
in it.
The general form of Lateral surface area Total surface area and Volume is:
Lateral surface area = perimeter of the base x height
Total surface area = LSA + 2 (base area)
Volume = Area of base x height
Important and commonly used solids are described below one after another:

Cube
1 Find the diagonal, lateral surface area,, total surface area and volume of a cube of side 4.5 cm.
side a = 4.5 cm

diagonal d = a unit
= 1.732 x 4.5
= 7.794 cm
L.S.A = 4a² unit²
= 4 x 4.5 x 4.5

= 81 cm²
T.S.A = 6a² unit
= 6 x 4.5 x 4.5
= 121.5 cm²

V = a³ unit³
= 4.5 x 4.5 x 4.5
= 91.125 cc.

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CITS : WCS - Electrical - Exercise 6