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18. The difference between outside and inside radii of a metallic cylindrical pipe of length 14 cm is 2 CM if the pipe is made of metal, find the outer and inner radii of the pipe |
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Answer» r= inner radius R= outer radius h= height of the metallic pipe = 14 cm Difference between the CURVED surface area of the outer CYLINDER and Curved surface area of the inner cylinder = 2πRh - 2πrh. Given: difference between the outside and inside curved surface area of cylinder=44 cm2 . so, 2πh( R - r) = 44 2 x 22/ 7 x 14 ( R - r) = 44 R - r = 1 / 2 = 0.5 Given: the pipe is made up of METAL= 99 cm³ Volume of cylindrical metallic pipe = πR²h - πr²h. so, 22/7 x 14 (R² - r²) = 99 44(R² - r²) = 99 (R² - r²) = 9 / 4 R²-r²= 2.25 ( R - r)(R + r) = 2.25 (0.5)(R + r) = 2.25 R + r = 2.25 / 0.5 R + r = 4.5 Adding up both the values we get 2R = 4.5 + 0.5 = 5 R = 2.5 cm and r = 2 cm
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