Question for the Physics-Minded

[beamjockey]

Recently I bought a new can of coffee.

I removed its plastic lid, and admired the shiny foil seal. On one side, ordinary atmospheric pressure. On the other, "vacuum." Its rim is attached to the circular rim of the can. The forces on it balance into a smooth convex form.


I began to wonder:

What shape is this?

Paraboloid? Section of a sphere?

I'm thinking it's a catenary of rotation. Am I right?

Comments

[harvey-rrit.livejournal.com]

I've read all these comments, and I'm certain you must be right. If it were a paraboloidal section, extending it far enough would make it come to an ogive point in the middle.

(I had to visualize somebody on Mercury blowing lead bubbles to figure this out.)