What mass of a material with density ρ is required to make a hollow spherical shell having inner radius r1 and outer radius r2? 


answer is =  


is given that :-
 Density of material =ρ
radius of inner spherical shell = r_1
radius of outer spherical shell=r_2
we know that the volume of sphere is \frac{4}{3}\pi r^{3}
Volume of the given spherical shell = \frac{4}{3}\pi( (r_2)^{3}-(r_1)^{3})
Then mass of the spherical shell can be calculate as:
Mass, m=density/ volume

 answer =