A solid sphere of radius 4cm has a mass of 64kg. What wil...
A solid sphere of radius 4cm has a mass of 64kg. What will be the mass of a shell of the same metal whose internal and external radii are 2cm and 3cm respectively?
5kg
16kg
19kg
6kg
Correct answer is A
1√3(12)2
= 4√3
= √3√3
= 4√3√3
m = 64kg, V = 4πr33
= 4π(4)33
= 256π3 x 10-6m3
density(P) = MassVolume
= 64256π3×10−6
= 64×3×10−6256
= 34×10−6
m = PV = 34π×10−6 x 43 π[32 - 22] x 10-6
34×10−6 x 43 x 5 x 10-6
= 5kg