Question

Find the mass of a metallic hollow cylindrical pipe 40 cm long with internal
diameter 20cm and made of 10mm thick metal ,if 1 centimetre cube of the
metal weights 7.5​

Answer 1

Answer:

We have,

l=40 cm

r=4 cm

R=12 cm

We know that the volume of the hollow cylinder

=π(R

2

−r

2

)h

So,

=π(12

2

−4

2

)×40

=π(144−16)×40

=π(128)×40 cm

3

Since, this hollow cylinder pipe is melted and cast into a solid cylinder which length is 20 cm and let the radius be r

So,

πr

2

×20=π(128)×40

r

2

=128×2

r

2

=256

r=16 cm

Hence, this is the answer.