Surface Areas And Volumes

A metallic right circular cone 20 cm high and whose vertical angle is 60° is cut into two parts at the middle of its height by a plane parallel to its base. If the frustum so obtained is drawn into a wire of diameter 1/16 cm, find the length of the wire.

Solution: Let $A B C$ be the metallic cone, $DECB$ is the required frustum Let the two radii of the frustum be$\mathrm{DO}^{\prime}=\mathrm{r}_{2}$ and $\mathrm{BO}=\mathrm{r}_{1}$From $\triangle...

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A container, opened from the top and made up of a metal sheet, is in the form of a frustum of a cone of height 16 cm with radii of its lower and upper ends as 8 cm and 20 cm, respectively. Find the cost of the milk which can completely fill the container, at the rate of Rs. 20 per litre. Also find the cost of metal sheet used to make the container, if it costs Rs. 8 per 100 cm2.

Given, r1 = 20 cm, r2 = 8 cm and h = 16 cm \[\therefore Volume\text{ }of\text{ }the\text{ }frustum\text{ }=\text{ }\left(  \right)\times \pi \times h\left( r12+r22+r1r2 \right)\] It is given that...

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A fez, the cap used by the Turks, is shaped like the frustum of a cone (see Fig.). If its radius on the open side is 10 cm, radius at the upper base is 4 cm and its slant height is 15 cm, find the area of material used for making it.

  Given, For the lower roundabout end, span $(r_1)$ = 10 cm For the upper roundabout end, span $(r_2)$ = 4 cm Inclination tallness (l) of frustum = 15 cm Presently, The space of material to be...

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A farmer connects a pipe of internal diameter 20 cm from a canal into a cylindrical tank in her field, which is 10 m in diameter and 2 m deep. If water flows through the pipe at the rate of 3 km/h, in how much time will the tank be filled?

Think about the accompanying graph Volume of water that streams in t minutes from pipe \[=\text{ }t\times 0.5\pi \text{ }m^3\] Volume of water that streams in t minutes from pipe = \[t\times 0.5\pi...

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A cylindrical bucket, 32 cm high and with radius of base 18 cm, is filled with sand. This bucket is emptied on the ground and a conical heap of sand is formed. If the height of the conical heap is 24 cm, find the radius and slant height of the heap.

The outline will be as- Given, Tallness $(h_1)$ of tube shaped piece of the pail = 32 cm Range $(r_1)$ of roundabout finish of the pail = 18 cm Tallness of the cone like pile $(h_2)$ = 24 cm...

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A container shaped like a right circular cylinder having diameter 12 cm and height 15 cm is full of ice cream. The ice cream is to be filled into cones of height 12 cm and diameter 6 cm, having a hemispherical shape on the top. Find the number of such cones which can be filled with ice cream.

Number of cones will be = Volume of chamber/Volume of frozen treat For the chamber part, Range = 12/2 = 6 cm Stature = 15 cm ∴ Volume of chamber \[=\text{ }\mathbf{\pi }\times \mathbf{r2}\times...

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A spherical glass vessel has a cylindrical neck 8 cm long, 2 cm in diameter; the diameter of the spherical part is 8.5 cm. By measuring the amount of water it holds, a child finds its volume to be 345 cm3. Check whether she is correct, taking the above as the inside measurements, and π = 3.14.

Given, For the chamber part, Height (h) = 8 cm and Radius (R) = (2/2) cm = 1 cm For the circular part, Radius (r) \[=\text{ }\left( 8.5/2 \right)\text{ }=\text{ }4.25\text{ }cm\] Presently, volume...

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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.

Here, the volume of water left will be = Volume of chamber – Volume of strong Given, Range of cone = 60 cm, Stature of cone = 120 cm Range of chamber = 60 cm Stature of chamber = 180 cm Range of...

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A solid iron pole consists of a cylinder of height 220 cm and base diameter 24 cm, which is surmounted by another cylinder of height 60 cm and radius 8 cm. Find the mass of the pole, given that 1 cm3 of iron has approximately 8 g mass.

Given, the tallness of the enormous chamber (H) = 220 cm Sweep of the base (R) \[=\text{ }24/12\text{ }=\text{ }12\text{ }cm\] Thus, the volume of the huge chamber = πR2H \[=\text{ }\pi \left( 12...

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A vessel is in the form of an inverted cone. Its height is 8 cm and the radius of its top, which is open, is 5 cm. It is filled with water up to the brim. 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.

For the cone, Range = 5 cm, Tallness = 8 cm Too, Range of circle = 0.5 cm The outline will resemble It is realized that, Volume of cone = volume of water in the cone \[=\text{ }\pi r^2h\text{...

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A pen stand made of wood is in the shape of a cuboid with four conical depressions to hold pens. The dimensions of the cuboid are 15 cm by 10 cm by 3.5 cm. The radius of each of the depressions is 0.5 cm and the depth is 1.4 cm. Find the volume of wood in the entire stand (see Fig.).

Volume of cuboid = length x width x tallness We know the cuboid's measurements as 15 cmx10 cmx3.5 cm Along these lines, the volume of the cuboid \[=\text{ }15\times10\times3.5\text{ }=\text{...

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A Gulab jamun contains sugar syrup up to about 30% of its volume. Find approximately how much syrup would be found in 45 Gulab jamuns, each shaped like a cylinder with two hemispherical ends with length 5 cm and diameter 2.8 cm (see figure).

It is realized that the gulab jamuns are like a chamber with two hemispherical finishes. Thus, the absolute stature of a gulab jamun = 5 cm. Measurement = 2.8 cm Thus, range = 1.4 cm ∴ The tallness...

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Rachel, an engineering student, was asked to make a model shaped like a cylinder with two cones attached at its two ends by using a thin aluminum sheet. The diameter of the model is 3 cm and its length is 12 cm. If each cone has a height of 2 cm, find the volume of air contained in the model that Rachel made. (Assume the outer and inner dimensions of the model to be nearly the same.)

Given, Height of each conical part $=2 cm$ Stature of chamber \[=\text{ }12{-}2{-}{2}\text{ }=\text{ }8\text{ }cm\] Span = 1.5 cm Stature of cone = 2 cm Presently, the all out volume of the air...

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A tent is in the shape of a cylinder surmounted by a conical top. If the height and diameter of the cylindrical part are 2.1 m and 4 m respectively, and the slant height of the top is 2.8 m, find the area of the canvas used for making the tent. Also, find the cost of the canvas of the tent at the rate of Rs 500 per m2. (Note that the base of the tent will not be covered with canvas.)

It is realized that a tent is a mix of chamber and a cone. From the inquiry we realize that Distance across = 4 m Inclination tallness of the cone (l) = 2.8 m Sweep of the cone (r) = Radius of...

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