Question

The diameter and the thickness of a hollow metals sphere are 12 cm and 0.01 m respectively. the density of the metal is 8.88 gm per cm³. find the outer surface area and the mass of the sphere?

Answer 1

Outer surface area of the sphere is= 4*pi*r^2

so Outer surface area is= 4* 22/7* 6*6 ( Since, D=12 and r=6)
So, outer surface area is 452.57cm^2

Now the mass = Volume * Density 
(Since density= mass/ Volume)
r1=6cm & r2= 6-1cm= 5cm
So volume= outer  sphere -  inner sphere
=(4*22/7*r1^2) - (4*22/7*r2^2)
outer sphere volume = 4*22/7 *6*6=452.57cm^3
Inner sphere volume = 4*22/7*5*5= 314.28cm^3
So volume = 452.57 - 314.28 = 138.29Cm^3
Mass= Volume * Density (Since, Density = Volume / Mass)
Mass = 138.29*8.8=1216.952

Answer 2

Answer:

outer surface area of sphere is 452.16cm square and mass of sphere is 3385.94gm .

for explanation refer to the attachment.