Example-13.
A cylindrical pencil is sharpened to produce a perfect cone at one end with no
over all loss of its length. The diameter of the pencil is 1cm and the length of the conical
portion is 2cm. Calculate the volume of the peels. Give your answer correct to two places if it is in decimal {use pir = 355/113}.
Solution :
Diameter of the pencil = 1cm
so , radius of the pencil (r) = 0.5 cm
Length of the conical portion = h = 2cm
Volume of peels = Volume of cylinder of length 2 cm and base radius 0.5 cm.
- volume of the cone formed by this cylinder
An iron pillar consists of a cylindrical portion of 2.8m height and 20cm in diameter and a cone of 42 cm height surmounting it. Find the weight of the pillar if 1 cm3 of iron weighs 7.5 g.
A toy is made in the form of hemisphere surmounted by a right cone who secircular base is joined with the plane surface of the hemisphere. The radius of the base of the cone is 7cm and its volume is 3/2 of the hemisphere. Calculate the height of the cone and the surface area of the toy correct to 2 places of decimal {Take pir=31/7} .
Find the volume of the largest right circular cone that can be cut out of a cube whose edge is7cm.
= pr2h-1pr2h = 2pr2h
33
1 cm.
= 2 ́355 ́(0.5)2 ́2cm3 =1.05cm3