Topic: Strength of Materials
A metal pipe of 1 m diameter contains a fluid having a pressure of 10 $kgf/cm^{2}$. If the permissible tensile stress in the metal is 200 $kgf/cm^{2}$ then the thickness of the metal required for making the pipe would be
- A. 5 mm
- B. 10 mm
- C. 25 mm
- D. 20 mm
Answer: C. 25 mm
Explanation: Given: diameter $d=1m = 100cm$, pressure $P=10~kgf/cm^{2}$, permissible tensile (hoop) stress $\sigma_{h}=200~kgf/cm^{2}$. The formula for hoop stress in a thin cylinder is $\sigma_{h}=\frac{Pd}{2t}$. Substituting the values: $200 = \frac{10\times100}{2\times t} \implies 200 = \frac{500}{t} \implies t = 2.5~cm = 25~mm$.