A cylindrical vessel of diameter $14cm$ and height $42cm$ is fixed symmetrically inside a similar vessel of diameter 16cm and height of $42cm$. The total space between the two vessels is filled with cork dust for heat insulation purposes. How many cubic cms of the cork dust will be required?
A cylindrical vessel of diameter $14cm$ and height $42cm$ is fixed symmetrically inside a similar vessel of diameter 16cm and height of $42cm$. The total space between the two vessels is filled with cork dust for heat insulation purposes. How many cubic cms of the cork dust will be required?

According to the question it is given that,

Depth of the cylindrical vessel = Height of the cylindrical vessel $=h=42cm$ (common for both)

Inner diameter of the cylindrical vessel $=14cm$

Thus, the inner radius of the cylindrical vessel $={{r}_{1}}=14/2=7cm$

Outer diameter of the cylindrical vessel $=16cm$

Now, the outer radius of the cylindrical vessel $={{r}_{2}}=16/2=8cm$

Then,

The volume of the cylindrical vessel

$V=\pi \left( r_{2}^{2}-r_{1}^{2} \right)\times h$

$=\pi \left( {{8}^{2}}-{{7}^{2}} \right)\times 42$

$=22/7\times 15\times 42$

$V=1980c{{m}^{3}}$

Hence, the total space between the two vessels is $1980c{{m}^{3}}$, which is also the amount of cork dust required.