Question

The mass of a solid sphere of metal 5cm in diameter is 6.25 kg. Find the mass of a spherical shell of same metal, the external diameter being 10cm and thickness 1 cm.

Answer 1

volume of the 5 cm sphere
= (4/3)π(5^3) = (500/3)π cm^3

volume of shell
= (4/3)π(10^3) - (4/3)π(8^3)
= (1952/3)π

since the mass is a function of the volume,

[ (1952/3)π] / [(500/3)π] = x/6.25
1952/500 = x/6.28
500x = 12200
x = 24.4 kg

check my arithmetic

Answer 2

volume of the 5/2 cm sphere
= (4/3)π(5/2^3) = (625/6)π cm^3

volume of shell
= (4/3)π(5^3) - (4/3)π(4^3)
= (244/3)π cm^3

since the mass is a function of the volume,

(625/6)π × X = (244/3)π × 6.25
X = 48.8kg

Answer 3

fak u

Answer 4

volume of the 5/2 cm sphere
= (4/3)π(5/2^3) = (625/6)π cm^3

volume of shell
= (4/3)π(5^3) - (4/3)π(4^3)
= (244/3)π cm^3

since the mass is a function of the volume,

(625/6)π × X = (244/3)π × 6.25
X = 48.8kg