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Ex 13.8, 3 - The diameter of a metallic ball is 4.2 cm - Ex 13.8

Ex 13.8, 3 - Chapter 13 Class 9 Surface Areas and Volumes - Part 2

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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·π‘–π‘Žπ‘šπ‘’π‘‘π‘’π‘Ÿ/2 = 4.2/2 = 2.1 cm Now, volume of the sphere = 4/3 Ο€r3 = 4/3 Γ— 22/7 Γ— 2.1 Γ— 2.1 Γ— 2.1 cm3 = 38.808 cm3 Now, Density = π‘€π‘Žπ‘ π‘ /π‘‰π‘œπ‘™π‘’π‘šπ‘’ 8.9 = π‘€π‘Žπ‘ π‘ /38.808 π‘€π‘Žπ‘ 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)

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