EXERCISE - 10.2
1. A closed cylindrical tank of height 1.4 m. and radius of the base is 56 cm.
is made up of a thick metal sheet. How much metal sheet is required (Express
in square meters)
3
2. The volume of a cylinder is 308 cm.. Its height is 8 cm. Find its lateral surface area
and total surface area.
3. A metal cuboid of dimension 22 cm. x 15 cm. x 7.5 cm. was melted and cast into a
Answers
Answered by
6
1.
Given, radius of the base of a cylinder r = 56cm = 0.56m
And height h = 1.4m
To find the metal sheet required, we need to find the total surface area of the cylinder.
Total surface area of the
cylinder = 2πr(r + h)
= 2 × π × 0.56 × (0.56 + 1.4)
= 6.89 ≃ 6.9m2
2.
Answer.
THEREFORE, LATERAL SURFACE AREA OF CYLINDER = 2πrh
= 2×22/7×154×8
= 7,744cm
3.
Given a metal cuboid of dimension length 22 cm breadth 15 cm and height is 7.5 cm
Then volume of cuboid =22×15×7.5=2475cm
3
If we melt this cuboid and cast in the cylinder of height 14cm
Then the volume of cuboid =volume of cylinder
Let r is a radius of a cylinder
Then volume of cylinder =πr
2
h=
7
22
×r
2
×14
∴
7
22
×r
2
×14=2475
⇒r
2
=
22×14
2475×7
=56.25
⇒r=7.5cm
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