Tag: hollow cylinder

Questions Related to hollow cylinder

What will be the volume of a sphere of diameter $15\ cm$? (Correct up to $2$ decimal place)

  1. $1436.76\ {cm}^{3}$

  2. $1767.15\ {cm}^{3}$

  3. $14137.17\ {cm}^{3}$

  4. $4188.79\ {cm}^{3}$


Correct Option: B
Explanation:

The Volume of a sphere$=\dfrac{4}{3}\pi \ \text{R}^{3}$
Here Radius $R=7.5 \ cm$
On solving We get Volume$=1767.15\ {cm}^{3}$ 

What will be the radius of a sphere whose surface area is 616 $cm^{2}$? (Use $\pi=\dfrac{22}{7}$)

  1. $6$ cm

  2. $7$ cm

  3. $8$ cm

  4. $9$ cm


Correct Option: B
Explanation:

Radius $=\dfrac{1}{2}\times\sqrt{\dfrac{\text{surface area}}{\pi}}$
on solving we get radius $=7$ cm

If volume of sphere is $850$ $m^{3}$ then its radius and surface area are

  1. $6m$, $450$ $m^{2}$

  2. $5m$, $560$ $m^{2}$

  3. $2m$, $780$ $m^{2}$

  4. $5.88m$, $434$ $m^{2}$


Correct Option: D
Explanation:
Volume of Sphere $=850m^3=\cfrac{4}{3}\pi r^3 \Rightarrow r^3=\cfrac{850\times 3\times 7}{4\times 22}=202.84 \\ \Rightarrow r=\sqrt[3]{202.84}=5.88m$
Surface area $=4\pi r^2=4\times \cfrac{22}{7}\times 5.88\times 5.88 \approx 434m^2$

 If the radius of a sphere is doubled, then what is the ratio of new to the old surface area?

  1. $1:2$

  2. $2:1$

  3. $1:4$

  4. $4:1$


Correct Option: D
Explanation:

$S _1=4\pi r^2 \ S _2=4\pi (2r)^2=16\pi r^2 \ \cfrac{S _2}{S _1}=\cfrac{16\pi r^2}{4\pi r^2}=\cfrac{4}{1} \Rightarrow 4:1$

A test-tube consists of a hollow cylindrical tube joined to a hemi-spherical bown of the same internal radius. The whole tube holds $350$ cc of water and in the cylindrical portion falls $1$ cm if $19.64$ cc of water is removed. Find the length of the cylindrical portion of the tube. (Take $\pi =$ $22/7$)

  1. $12.15$ cm

  2. $16.15 $ cm

  3. $24.15 $ cm

  4. None of these


Correct Option: B
Explanation:

Let r cm. be the radius of the hemisphere and h cm be the length of the cylindrical portion.
Volume of water removed $\pi r^2 (1) = 19.64cc$
$\Rightarrow r^2 = 19.64 \times \displaystyle \frac{7}{22}  \Rightarrow r = 2.5 cm$
Volume of the whole tube $= \pi r^2 h + \displaystyle \frac{2}{h} \pi r^3 = 350 c.c.$
$\Rightarrow \pi r^2 \displaystyle \left ( h + \frac{2}{3} r \right ) = 350$
$\Rightarrow \displaystyle \frac{22}{7} \times 2.5^2 \times \left ( h + \frac{2}{3} \times 2.5 \right ) = 350$
$\displaystyle \frac{22}{7} \times 6.25 \times (h+ 1.67) = 350 $
$ \Rightarrow \displaystyle 350 \times \frac{7}{22} \times 6. 25 - 1.67 cm    \Rightarrow h = 16.15 cm$

The height of a hollow cylinder is $14cm$ if external diameter is $16cm$ and total curved surface area of the hollow cylinder is $1320sq.cm$, then its internal diameter is

  1. $14cm$

  2. $16cm$

  3. $7cm$

  4. $8cm$


Correct Option: C
Explanation:

Given     

external radius $r _2=8$, height of cylinder $h=14$
 we have,


$2\pi h(r _{1}+r _{2})=1320$

$ \implies8+r _1=\displaystyle \frac{1320\times7}{2\times22\times14}$

$\implies r _1=7cm$

The ratio between the radius of the base and the height of a cylinder is $2:3$. If its volume is $12936$ cu. cm, the total  surface area of the cylinder is :

  1. $2587.2 c{m^2}$

  2. $3080 c{m^2}$

  3. $25872 c{m^2}$

  4. $38808 c{m^2}$


Correct Option: B
Explanation:
We have $\dfrac{r}{h}=\dfrac{2}{3}\Rightarrow\,h=\dfrac{3r}{2}$

Volume of a cylinder$=\pi{r}^{2}h$

$\Rightarrow\,12936=\dfrac{22}{7}\times{r}^{2}\times \dfrac{3r}{2}$

$\Rightarrow\,12936=\dfrac{11\times 3}{7}{r}^{3}$

$\Rightarrow\,{r}^{3}=\dfrac{12936\times 7}{33}=2744$

$\Rightarrow\,r=\sqrt[3]{2744}=14\ cm$

We have $h=\dfrac{3r}{2}=\dfrac{3\times 14}{2}=21\ cm$

Total Surface area$=2\pi\,r\left(r+h\right)=2\times\dfrac{22}{7}\times 14\left(14+21\right)=2\times\dfrac{22}{7}\times 14\times 35=140\times 22=3080\ sq.cm$

A cylinder and cone of equal base radius and equal height are given. Which of the following statement is true/

  1. Volume of cylinder and cone are equal

  2. Volume of cylinder is one-third of volume of cone

  3. Volume of cone is half of the volume of cylinder

  4. Volume of cone is one-third of volume of cylinder


Correct Option: A

Find the volume of a solid cylinder whose radius is $14$cm and height $30$cm

  1. $18380cm^3$

  2. $18480cm^3$

  3. $18580cm^3$

  4. $18680cm^3$


Correct Option: A

the radii of two cylinders are in the ratio 2:3 and their height are in the ratio 5:3. ratio of their volume

  1. $20:27$

  2. $10:9$

  3. $18:13$

  4. $9:20$


Correct Option: A