Question

A Foot ball is inflated to a gage pressure of 80 kPa. Which has an outside diameter of 185 mm and a wall thickness of 3 mm. The hoop stress in the ball is

• A. 1.695 MPa
• B. 1.233 MPa
• C. 1.213 MPa
• D. 1.193 MPa

Answer 1

The correct option is D 1.193 MPa

Given data:
Outside diameter = 185 mm
thickness (t) = 3 mm
Inside diameter (D) = 185 - 2 ( 3)
= 179 mm

Hoop stress $\left({\sigma }_n\right)=\frac{P.d}{4t}$

$=\frac{0.08\times 179}{4\times 3}$

$=1.193MPa$