Question

8) The volume of metallic ylindrical pipe is 770cm .It's length is 14cm and it's external radius is 9cm .Then itss thickness

Answer 1

Answer:

The volume of a cylindrical pipe is 748 cm^{3}cm

3

Then its thickness is 8 cm

Solution:

Given that:

Height of the cylindrical pipe (h) = 14cm

Let the external radius of the cylindrical pipe be “R” = 9 cm

Let the internal radius be “r”

Volume of cylindrical pipe = 748 cm^{3}cm

3

Volume of cylinder when external and internal radius are given is:

\text { Volume }=\pi h\left(R^{2}-r^{2}\right) Volume =πh(R

2

−r

2

)

Substituting the values we can find the thickness of pipe “r”:

$$\begin{lgathered}\begin{array}{l}{748=\pi \times 14\left(9^{2}-r^{2}\right)} \\\\ {748=\frac{22}{7} \times 14\left(81-r^{2}\right)} \\\\ {748=44\left(81-r^{2}\right)} \\\\ {\frac{748}{44}=81-r^{2}} \\\\ {17=81-r^{2}} \\\\ {r^{2}=81-17=64}\end{array}\end{lgathered}$$

r = 8 cm

Thus the thickness of pipe is 8 cm