# Mechanical Engineering - Strength of Materials - Discussion

Discussion Forum : Strength of Materials - Section 2 (Q.No. 7)
7.
When a thin cylindrical shell is subjected to an internal pressure, there will be
a decrease in diameter and length of the shell
an increase in diameter and decrease in length of the shell
a decrease in diameter and increase in length of the shell
an increase in diameter and length of the shell
Explanation:
No answer description is available. Let's discuss.
Discussion:
14 comments Page 1 of 2.

Shubham jalan said:   4 years ago
Thanks for explaining @Kar Tariq.

Harshad patel said:   5 years ago
Good explanation, thanks @Nainesh.

Kar tariq said:   5 years ago
When a thin shell is subjected to an internal pressure. Hoop stress developed is tensile therefore increase in dia also. Longitudinal stress developed is a tensile therefore increase in length also. So the correct answer is Option D.
(2)

Balaji said:   6 years ago
Pd/4t is the formula for a thin cylindrical shell. So, p is directly proportional to d wherever d=2l.
(1)

Sridevi said:   7 years ago
Answer is correct both length and diameter increases as pressure is acting uniform in all direction. It is not an axial force to increase the length and decrease diameter.

D rahul said:   8 years ago
I think in thin cylindrical shells the (radial stress is) & (longitudinal stress). So, the diameter must increase and length should decrease.

It is an option (b).

Vitthal said:   8 years ago
Pressure acting uniformly over entire inside area which tends it not to contract.

Aman Bansal said:   10 years ago
Due to internal pressure, both d & L will increase as volume will also increase.

D' Nainesh said:   10 years ago
Its simple logic. When we blow air into balloon, its whole (3D) dimension will increase. Because the pressure inside it is uniformly distributed over its entire internal area.

Same concept is here. Here the internal pressure is not uniaxial in which longitudinal dimension will increase and lateral will decrease. It is of 3 dimensional. So given answer is correct.

HARDIK said:   10 years ago
Pressure depend on volume of cylinder, so both is uniformly increasing. All related data is constant. So this is correct.