Volume and Surface Area of Solid Figures
- A cylindrical jar, whose base has a radius of 15 cm, is filled with water upto a height of 20 cm, A solid iron spherical ball of radius 10 cm is dropped in the jar to submerge completely in water. Find the increase in the level of water (in cm). ?
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Let level of water will be increased by h cm
π x (15)2 x h = (4/3)π(10)3Correct Option: D
Let level of water will be increased by h cm
π x (15)2 x h = (4/3)π(10)3
∴ h = [(4/3) x 10 x 10 x 10] / [15 x 15]
= 525/27 cm
- Water flows at the rate of 10 m/min from a cylindrical pipe 5 mm in diameter. How long will it take to fill up a conical vessel whose diameter at the base is 40 cm and depth is 24 cm ?
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Given, radius of pipe 5/2 x 10 = 5/20 cm [∵ 1 cm = 10 mm]
Height of pipe = 1000 cm
Radius of vessel = 20 cm and height = 24 cm
Volume of water flow in one minute from cylindrical pipe = π (5/20)2 x 1000
= 125/2 π cm3
and volume of conical vessel = 1/3 π(20)2 x 24 = 3200π cm3
∴ Required time = (3200π x 2) / 125πCorrect Option: A
Given, radius of pipe 5/2 x 10 = 5/20 cm [∵ 1 cm = 10 mm]
Height of pipe = 1000 cm
Radius of vessel = 20 cm and height = 24 cm
Volume of water flow in one minute from cylindrical pipe = π (5/20)2 x 1000
= 125/2 π cm3
and volume of conical vessel = 1/3 π(20)2 x 24 = 3200π cm3
∴ Required time = (3200π x 2) / 125π
= 511/5 or 51 min 12 s
- In a shower, 10 cm of rain falls, What will be the volume of water that falls on 1 hect area of ground ?
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1 hec = 10000 m3
Volume of water = Base area x HeightCorrect Option: C
1 hec = 10000 m3
Volume of water = Base area x Height
= (10000 x 10)/100 = 1000 m3
- The radius of a sphere and a right circular cylinder are equal and their curved surface areas are also equal. The ratio of their volumes is ?
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Given, 4πr2 = 2πrh
∴ h = 2r
Now, required ratio
= 4/3πr3 : πr2hCorrect Option: B
Given, 4πr2 = 2πrh
∴ h = 2r
Now, required ratio
= 4/3πr3 : πr2h
= 4r : 3h
= 4r : 6r [ ∴ h = 2r]
= 2 : 3
- How many spherical bullets can be made out of a solid cube whose edge measures 44 cm, each bullet being 4 cm in diameter ?
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Volume of 1 bullet = 4/3π(2)3 = (32/3 x 22/7) cm3
Volume of the cube = (44)3Correct Option: B
Volume of 1 bullet = 4/3π(2)3 = (32/3 x 22/7) cm3
Volume of the cube = (44)3
∴ Number of bullets = Volume of solid/Volume of 1 bullet
= (44)3 x 3 x 7 / 32 x 22 = 2541