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Question
The diameters of the lower and upper ends of a bucket in the form of a frustum of a cone are 10 cm and 30 cm respectively. If its height is 24 cm, find:
1) The area of the metal sheet used to make the bucket.
2) Why we should avoid the bucket made by ordinary plastic? [Use π = 3.14]
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Solution
We have:
A radius of the upper end of the frustum, R = 15 cm; Radius of the lower end of the frustum, r = 5 cm; Height of frustum, h = 24 cm
we know
Slant height, `l^2 = h^2 + (R - r)^2`
`=> l^2 = ((24)^2 + (15 - 5)^2) = (576 + 100) = 676`
`= l = 26 cm`
1) Required area of the metal sheet = `pi[r^2 + 1(R + r)]` sq. cm
`= 3.14 [5^2 + 26(15 + 5)] cm^2`
`= 3.14 xx (25 + 520) cm^2`
`= 3.14 xx 545 cm^2`
`= 1711.3 cm^3`
2) Plastic is harmful to the environment and to protect the environment its use should be avoided.
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Khurja is a city in the Indian state of Uttar Pradesh famous for the pottery. Khurja pottery is traditional Indian pottery work which has attracted Indians as well as foreigners with a variety of tea sets, crockery and ceramic tile works. A huge portion of the ceramics used in the country is supplied by Khurja and is also referred as "The Ceramic Town". One of the private schools of Bulandshahr organised an Educational Tour for class 10 students to Khurja. Students were very excited about the trip. Following are the few pottery objects of Khurja.
Students found the shapes of the objects very interesting and they could easily relate them with mathematical shapes viz sphere, hemisphere, cylinder etc. |
Maths teacher who was accompanying the students asked the following questions:
- The internal radius of hemispherical bowl (filled completely with water) in I is 9 cm and the radius and height of the cylindrical jar in II are 1.5 cm and 4 cm respectively. If the hemispherical bowl is to be emptied in cylindrical jars, then how many cylindrical jars are required?
- If in the cylindrical jar full of water, a conical funnel of the same height and same diameter is immersed, then how much water will flow out of the jar?
