Question

Radius of an iron sphere is 0.21 cm .if density of iron is 7.80g/cc,calculate its mass

Answer 1

volume of iron sphere = 4/3πr³
= 4/3× 22/7 × (0.21)³ cm³
=4× 22× 0.1 ×0.0441 cm³
=0.38808 cm ³

density = mass/volume
mass = density × volume
= 7.8 × 0.38808 g
=3.02 g

Answer 2

Hi there !!

Radius = r = 0.21cm

Density = 7.80 g/ cm³

Volume of a sphere = 4/3πr³
                                = 4/3 × 22/7 × 0.21 × 0.21 × 0.21
                                = 0.38808 cm ³ 

Density = Mass ÷ Volume

Mass = Density × Volume 
          = 7.80 ×  0.38808
          = 3.02 grams [ approx.]