Solution to Home Assignment of Surface area & Volu

Home Assignment:Areas Related to Circles: : Home Assignment:Areas Related to Circles: 1. Hint for the Solution:- No of small spherical balls =volume of iron sphere / volume of each ball =27 An iron solid sphere of radius 3cm is melted and recast into small spherical balls of radius 1cm each. Assuming that there is no wastage in the process, find the number of small spherical balls made from the given sphere.

Slide 2 : 2. Hint for the Solution:- 2 ∏ rh + 2∏rxr = 2 ∏ r (r + h) Hence the surface area is = 2 X 22/7 X 30 (145 + 30) = 33000 sq cm = 3.3 sq.m Raju made a bird-bath for his garden in the shape of a cylinder with a hemispherical depression at one end (see Fig). The height of the cylinder is 1.45 m and its radius is 30 cm. Find the total surface area of the bird-bath. (Take π = 22/7 )

Slide 3 : Hint of the Solution:- Volume= ∏ rxrxh + 1/3∏rxrxh = ∏ rxr (h + 1/3h) = ∏x8x8 (240 + 1/3x36) = ∏x8x8 (240 + 12) =22/7x64x252 =50688 cu cm. Therefore, weight = 50695.5 g 3. An iron pillar has lower part in the form of a right circular cylinder and the upper part in the form of a right circular cone. The radius of the base of each of the cone and cylinder is 8 cm. The cylindrical part is 240 cm high and the conical part is 36 cm high. Find the weight of the pillar if 1cubic cm of iron weighs 7.5 grams. (Take = 22/7)

Slide 4 : Thank you