Question

The diameter of a metallic ball is 4.2 cm. If the density of the metal is 8.9 cm3, find the mass of the ball.

Answer 1

volume of metallic ball =4/3 pi.r^3
=4/3 x 22/7 x (4.2/2)^3
=4/3 x 22/7 x 2.1 x 2.1 x 2.1
=38.808 cm^3
now,
density =mass/volume
8.9 g/cm^3=mass/38.808 cm^3
mass =38.808 x 8.9 g
=345.39 g

Answer 2

Diameter of the ball = 4.2 cm
Radius = 4.2/2 = 2.1 cm

Volume of the ball ---> 4/3πr^3
4/3 x 22/7 x 2.1 x 2.1 x 2.1 = 38.808 cm^3

Volume = Mass / Density
Mass = Volume x Density
Mass = 38.808 x 8.9 = 345.3912 g