So first, to compute the stresses we'll need the areas,

so we'll compute the areas.

So the area of the top portion, Ab, is pi by 4, D squared,

the outer squared minus the inner diameter squared

is equal to that, and substituting in the numbers,

we find that that is equal to 679x10^-6 m^2.

Similarly, the cross-sectional area of the lower

portion BC is pi by 4 outer diameter squared minus inner diameter squared,

which is equal to 1442x10^-6 m^2.

Now we're ready to compute the stresses.

So the stress in the upper portion here, sigma Ab, is the force divided by area.

And if I imagine a hypothetical cut through the upper section here,

and I apply a free body diagram to that upper section, I see that the compressive

force in that upper region is constant, and equal to the applied force, P1.

So sigma Ab is P1 over Ab.