A cylindrical vessel of diameter 14 cm and height 42 cm is fixed symmetrically inside a similar vessel of diameter 16 cm and height 42 cm. The total space between the two vessels is filled with cork dust for heat insulation purposes. How many cubic centimeters of cork dust will be required?
Given height of cylindrical vessel (h) = 42 cm
Inner radius of vessel (r’) = 
cm =7 cm
Outer radius of vessel (r’’) = 
=8 cm
Volume of cylinder = π (r’’2 – r’2) h
= π (82 - 72) 42
= 1980 cm3
15