Question

An iron pipe is 21 m long and its exterior diameter is 8 cm. If the thickness of the
pipe is 1 cm and iron weight is 8 g/cm?, find the weight of pipe.​

Answer 1

Given:-

• Height of the pipe = 21m = 2100cm

• Exterior Radius(R)= 8/2 = 4cm

• Thickness of the pipe = 1cm

• Internal radius (r) = external radius - Thickness = 4 - 1 = 3cm.

• Weight of iron = 8g/cm.

To Find:-

• The weight of the Pipe

Formula used:-

• Volume of Cylinder = πr²h

Now,

→ Volume of pipe = Volume of external cylinder - Volume of internal cylinder.

→ Volume of pipe = πR²h - πr²h

→ πh ( R² - r² )

→ $\rm{\dfrac{22}{7}\times{210} ( 4^2 - 3^2)}$

→ $\rm{22\times{300} ( 16 - 9)}$

→ $\rm{ 6600\times{7}}$

→ $\rm{ 46200cm^{3}}$.

Hence, The Volume of the pipe is 46200cm³.

→ weight of iron pipe per cm = 8g

Now,

→ Weight of 4620cm³ Pipe = 46200 × 8 = 369600g

Hence, The weight of pipe is 369.60kg

Answer 2

Answer:

lenght=21m=21*100=2100cm which is height (* means multiplied)

exterior diameter=8cm

radius=d/2

=8/2

=4cm

let us take exteror radius as R

thickness=1cm

iterior radius=exteriror(outer) radius-thickness

                   =4-1

                    =3cm(let inner radius be r

volume of pipe (which is hollow)=π(R squrae-r squrae)*height

                                                  =22/7(4 squrae-3 squrae)*2100

                                                   =22/7(16-9)*2100

                                                    =22/7*7*2100

                                                    =46200cubic cm

weight = 46200*8

          =369600gram

           =369.6kilogram