__Surface Area and Volume __

__Conversion of one solid into another solid__

Some time we have to melt one solid and convert it to another shap. For example we have to convert a metallic sphere to wire in the form of cylinder. The earth taken out from a well and is spreed around to make embankment of the form of cylindrical shell.

**Example 1.** A rectangular sheet of paper 44cm X 18cm is rolled along its length and a cylinder is formed. Find the volume of the cylinder.

**Solution:- **

Let height, h of the cylinder be 18cm

Circumference of the base

Now,

Volume of the cylinder =

**Example 2.** How many metres of cloth 1.1m wide will be required to make a conical tent whose vertical height is 12cm and base radius is 16m? Find also the cost of the cloth used at the rate of Rs. 14 per metre.

**Solution:- **Radius, r of base of conical tent = 16m.

Height, h of tent = 12m

Slant height l =

Curved surface area of the tent

Area of cloth = 7040/7 m

^{2}Width of the cloth = 1.1m

Lenght of the cloth = Area/width

Cost of 6400/7m cloth = Rs. 14 X 6400/7 = Rs. 12800.

Maths by Mr. M. P. Keshari

Subjects |
Maths (Part-1) by Mr. M. P. Keshari |

Chapter 9 |
Circle |

Chapter 10 |
Tangents to a circle |

Chapter 11 |
Geometrical Construction |

Chapter 12 |
Troigonometry |

Chapter 13 |
Height and Distance |

Chapter 14 |
Mensuration |

Chapter 15 |
Statistics |

Chapter 16 |
Probability |

Chapter 17 |
Co-ordinate Geometry |