Lateral Surface Area of a Cylinder


 
 
Concept Explanation
 

Lateral Surface Area of a Cylinder

Lateral surface area of cylinder: The curved surface joining the two bases of a right circular cylinder is called its lateral surface.

The lateral surface area of cylinder = small 2pi rh ; sq.;units

Illustration: The curved surface area of a right circular cylinder of height 14 cm is 88;cm^{2}. Find the diameter of the base of the cylinder.

Solution: Let r be the radius and h be the height of the cylinder.

Then,  2pi rh=88

small 2times frac{22}{7}times rtimes 14=88

88r =88

then r = 1 cm

Diameter of cylinder = 2 cm

Illustration: The diameter of a roller 120 cm long is 84 cm. If it takes 500 complete revolutions to level a playground, determine the cost of levelling it at the rate of 30 paise per square meter .

Solution: Clearly, the roller is a right circular cylinder of height h = 120 cm and radius of its base = r = 42 cm

So, area covered by the roller in one revolution = Curved surface area of the roller

                                                                   =2times frac{22}{7}times 42 times 120

                                                                   =31680;cm^{2}

So, area covered by the roller is 500 revolutions  =(31680times 500);cm^{2}

                                                                         =frac{(31680times 500)}{100times 100};m^{2}

                                                                         =1584;m^{2}

Hence, the cost of levelling the playground = =Rs;1584times frac{30}{100};m^{2}

                                                              =Rs;475.20

Sample Questions
(More Questions for each concept available in Login)
Question : 1

A right circular cylindrical tunnel of diameter 2 m and length 40 m is to be constructed from a sheet of iron. The area of the iron sheet required in m^2, is _____________________

Right Option : B
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Explanation
Question : 2

Savitri had to make a model of cylindrical Kaleidoscope for her science project. She wanted to use chart paper to make the curved surface of the kaleidoscope. What should be the area of chart paper required by her, if she wanted to make a kaleidoscope of length 25 cm with a 3.5 cm radius?

Right Option : B
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Explanation
Question : 3

20 cylindrical pillars of a building are to be cleaned. If the diameter of each pillar is 0.5 m and height is 4 m. What will be the cost of cleaning them at the rate of Rs. 2.50 per sq m.?

Right Option : A
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Explanation
 
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