Cylinder, Cone and Sphere (Surface Area and Volume)

The cross-section of a tunnel is a square of side 7 m surmounted by a semicircle as shown in the following figure.The tunnel is 80 m long. Calculate: (i) its volume (ii) the surface area of the tunnel (excluding the floor)

FIGURE: Side of square (a) = 7m the radius of semi-circle = 7/2 m Length of the tunnel = 80 m \[\begin{array}{*{35}{l}} Area\text{ }of\text{ }cross\text{ }section\text{ }of\text{ }the\text{...

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In the following diagram a rectangular platform with a semicircular end on one side is 22 meters long from one end to the other end. If the length of the half circumference is 11 meters, find the cost of constructing the platform, 1.5 meters high at the rate of Rs 4 per cubic meters.

Length of the platform = 22 m Circumference of semi-circle (c) = 11 m \[\begin{array}{*{35}{l}} radius\text{ }=\text{ }\left( c\text{ x }2 \right)/\text{ }\left( 2\text{ x }\pi  \right)\text{...

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An iron pole consisting of a cylindrical portion 110 cm high and of base diameter 12 cm is surmounted by a cone 9 cm high. Find the mass of the pole, given that 1 cm3 of iron has 8 gm of mass (approx). (Take π = 355/113)

Radius of the base of poles (r) = 6 cm Height of the cylindrical part (h1) = 110 cm Height of the conical part (h2) = 9 cm \[\begin{array}{*{35}{l}} Total\text{ }volume\text{ }of\text{ }the\text{...

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A right circular cylinder having diameter 12 cm and height 15 cm is full of ice-cream. The ice-cream is to be filled in identical cones of height 12 cm and diameter 6 cm having a hemi-spherical shape on the top. Find the number of cones required.

Diameter of the cylinder = 12 cm => radius = 6 cm Height of the cylinder = 15 cm Diameter of the cone = 6 cm =>radius = 3 cm Height of the cone = 12 cm Radius of the hemisphere = 3 cm Let the...

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A wooden toy is in the shape of a cone mounted on a cylinder as shown alongside. If the height of the cone is 24 cm, the total height of the toy is 60 cm and the radius of the base of the cone = twice the radius of the base of the cylinder = 10 cm; find the total surface area of the toy. [Take π = 3.14]

Height of the cone (h) = 24 cm Height of the cylinder (H) = 36 cm Radius of the cone (r) = twice the radius of the cylinder = 10 cm Radius of the cylinder (R) = 5 cm \[\begin{array}{*{35}{l}}...

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A vessel is a hollow cylinder fitted with a hemispherical bottom of the same base. The depth of the cylindrical part is 4(2/3) m and the diameter of hemisphere is 3.5 m. Calculate the capacity and the internal surface area of the vessel.

Diameter of the base = 3.5 m So, its radius = 3.5/2 m = 1.75 m = 7/4 m Height of cylindrical part = 4 + 2/3 = 14/3 (i) \[\begin{array}{*{35}{l}} Capacity\text{ }\left( volume \right)\text{ }of\text{...

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A circus tent is cylindrical to a height of 8 m surmounted by a conical part. If total height of the tent is 13 m and the diameter of its base is 24 m; calculate: (i) total surface area of the tent (ii) area of canvas, required to make this tent allowing 10% of the canvas used for folds and stitching.

Height of the cylindrical part = H = 8 m Height of the conical part = h = (13 – 8) m = 5 m Diameter = 24 m Its radius \[\begin{array}{*{35}{l}} =\text{ }24/2\text{ }=\text{ }12\text{ }m  \\...

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A circus tent is cylindrical to a height of 4 m and conical above it. If its diameter is 105 m and its slant height is 80 m, calculate the total area of canvas required. Also, find the total cost of canvas used at Rs 15 per meter if the width is 1.5 m

Radius of the cylindrical part of the tent (r) =105/2 m Slant height (l) = 80 m the total curved surface area of the tent \[\begin{array}{*{35}{l}} =\text{ }2\pi r\text{ }h\text{ }+\text{ }\pi rl ...

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A vessel is in the form of an inverted cone. Its height is 8 cm and the radius of the top which is open is 5 cm. It is filled with water up to the rim. When lead shots, each of which is a sphere of radius 0.5 cm, are dropped into the vessel, one-fourth of the water flows out. Find the number of lead shots dropped in the vessel.

Height of cone = 8 cm Radius = 5 cm \[\begin{array}{*{35}{l}} Volume\text{ }=~1/3\text{ }\pi {{r}^{2~}}h  \\ =\text{ }1/3\text{ x }22/7\text{ x }5\text{ x }5\text{ x }8\text{ }c{{m}^{3}}  \\ =\text{...

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A buoy is made in the form of a hemisphere surmounted by a right cone whose circular base coincides with the plane surface of the hemisphere. The radius of the base of the cone is 3.5 m and its volume is two-third of the hemisphere. Calculate the height of the cone and the surface area of the buoy, correct to two decimal places.

Radius of the hemisphere part (r) = 3.5 m = 7/2 m Volume of hemisphere \[\begin{array}{*{35}{l}} =\text{ }2/3\text{ }\pi {{r}^{3}}  \\ =\text{ }2/3\text{ x }22/7\text{ x }7/2x\text{ }7/2\text{ x...

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A hemi-spherical bowl of internal radius 9 cm is full of liquid. This liquid is to be filled into conical shaped small containers each of diameter 3 cm and height 4 cm. How many containers are necessary to empty the bowl?

Radius of hemispherical bowl = 9 cm \[Volume\text{ }=\text{ }2/3\text{ }\pi {{r}^{3}}~=\text{ }2/3\text{ }\pi {{9}^{3}}~=\text{ }2/3\text{ }\pi \text{ }x\text{ }729\text{ }=\text{ }486\text{ }\pi...

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The radii of the internal and external surfaces of a metallic spherical shell are 3 cm and 5 cm respectively. It is melted and recast into a solid right circular cone of height 32 cm. find the diameter of the base of the cone.

Height of the solid right circular cone = 32 cm Internal radius metallic spherical shell = 3 cm External radius spherical shell = 5 cm the volume of the spherical shell \[\begin{array}{*{35}{l}}...

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Find the minimum length in cm and correct to nearest whole number of the thin metal sheet required to make a hollow and closed cylindrical box of diameter 20 cm and height 35 cm. Given that the width of the metal sheet is 1 m. Also, find the cost of the sheet at the rate of Rs. 56 per m. Find the area of metal sheet required, if 10% of it is wasted in cutting, overlapping, etc.

Height of the cylinder box = h = 35 cm Base radius of the cylinder box = r = 10 cm Width of metal sheet = 1m = 100 cm Area of metal sheet required = total surface area of the box Length x width =...

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A cylindrical container with diameter of base 42 cm contains sufficient water to submerge a rectangular solid of iron with dimensions 22 cm x 14 cm x 10.5 cm. Find the rise in level of the water when the solid is submerged.

Diameter of cylindrical container = 42 cm it’s radius (r) = 21 cm Dimensions of rectangular solid = 22cm x 14cm x 10.5cm The volume of solid = 22 x 14 x 10.5 cm3 ….. (i) Let the height of water = h...

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A cylinder has a diameter of 20 cm. The area of curved surface is 100 sq cm. Find: (i) the height of the cylinder correct to one decimal place. (ii) the volume of the cylinder correct to one decimal place.

The diameter of the cylinder = 20 cm the radius (r) = 10 cm and the curved surface area = 100 cm2 Height = h cm (i) Curved surface area \[\begin{array}{*{35}{l}} =\text{ }2\pi rh  \\ 2\pi rh\text{...

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A cylinder of circumference 8 cm and length 21 cm rolls without sliding for 4½ seconds at the rate of 9 complete rounds per second. Find: (i) distance travelled by the cylinder in 4½ seconds, and (ii) the area covered by the cylinder in 4½ seconds

Base circumference of cylinder (c) = 8 cm So, the radius \[=\text{ }c/2\pi \text{ }=\text{ }\left( 8\text{ x }7 \right)/\text{ }\left( 2\text{ x }22 \right)\text{ }=\text{ }14/11\text{ }cm\] Length...

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