Ex 13.2, 7 - A solid consists of a cone of height 120 cm - Volume - Added

  1. Chapter 13 Class 10 Surface Areas and Volumes
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Ex 13.2, 7 A solid consisting of a right circular cone of height 120 cm and radius 60 cm standing on a hemisphere of radius 60 cm is placed upright in a right circular cylinder full of water such that it touches the bottom. Find the volume of water left in the cylinder, if the radius of the cylinder is 60 cm and its height is 180 cm. Volume of water left in cylinder = Volume of cylinder – Volume of solid Volume of cylinder Radius = r = 60 cm Height = h = 180 cm Volume of outer cylinder = 𝜋𝑟2ℎ = 22/7 × (60)2 × 180 = 14256000/7 Volume of solid Volume of solid = Volume of cone + volume of hemisphere Volume of cone Radius = r = 60 cm Height = h = 120 cm Volume of cone = 1/3 𝜋𝑟2ℎ = 1/3×22/7×(60)2×12 = 316800/7 cm3 Volume of hemisphere, Radius = r = 60 cm Volume of hemisphere = 2/3 𝜋𝑟3 = 2/3×22/7×603 = 3168000/7 cm3 Hence, Volume of solid = Volume of cone + Volume of hemisphere = 316800/7+3168000/7 = 6336000/7 cm3 Now, Volume of water left in cylinder = Volume of cylinder – Volume of solid = 14256000/7−6336000/7 = (14256000 − 6336000)/7 = (7920000/7) cm3 = 1131428.57 cm3 = 1131428.57 ×(1/100 m)^3 = 1131428.57×1/100×1/100×1/100 m3 = 1.131 m3 (approximately)

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  • sachin kumar's image

    Screenshot_2018-01-31-15-42-58-398_com.teachoo.teachoo.png      sir please see that.  In the formula of finding the volume of cone there is height of cone 120cm but while applying formula you changed this value to 12cm..... Why?  Please answer... 


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