Chapter 13 Class 9 Surface Areas and Volumes (Term 2)

Serial order wise

Last updated at May 29, 2018 by Teachoo

Ex 13.8,3 The diameter of a metallic ball is 4.2 cm. What is the mass of the ball, if the density of the metal is 8.9 g per cm3? To find mass, we have to find volume of sphere Radius of sphere = r = π·πππππ‘ππ/2 = 4.2/2 = 2.1 cm Now, volume of the sphere = 4/3 Οr3 = 4/3 Γ 22/7 Γ 2.1 Γ 2.1 Γ 2.1 cm3 = 38.808 cm3 Now, Density = πππ π /ππππ’ππ 8.9 = πππ π /38.808 πππ π /38.808 = 8.9 Mass = (38.808 Γ 8.9) g Mass = 345.3912 g. Mass = 345.39g (approx) Therefore, mass of metallic ball is is 345.39g (approx)