One end of a uniform rod of mass M and cross-sectional area A is suspended from a rigid support and an equal mass M is suspended from the other end, what is the stress at the mid point of the rod.

Explanation

Since the rod is uniform, half of its wieght can be taken to act at its mid point. For mid point of rod, the total weight suspended, F=weight of suspended mass + weight of half rod
`=Mg + (Mg)/(2) = 3/2 Mg`
`:.` Stress at the mid point, `S=F/A = (3 Mg)/(2A)`.