Answer: The volume of shell is 12.8π mm².
Step-by-step explanation:
Since we have given that
Radius to the inside of the shell = 4 milimeters
Radius to the outside of the shell = 4.2 milimeters
Since r changes from 4 mm to 4.2 mm
so, [tex]dr=4.2-4=0.2\ mm[/tex]
As we know that
Volume of shell is given by
[tex]\dfrac{4}{3}\pi r^3[/tex]
[tex]dv=\dfrac{4}{3}\pi 3r^2\ dr\\\\dv=4r^2\pi\ dr\\\\dv=4(16)\times 0.2\pi\\\\dv=12.8\pi[/tex]
So, the volume of shell is 12.8π mm².