I teach a class

November 10, 2012

I’m teaching a class on mechanics. Analytical mechanics. Torqued, not shaken. (That’s covered in, I shit you not, a class on vibrations.) I’m at the board, giving a lecture.

“Now, as you can see, if we have a shaft with non-constant cross sectional area, we know that the polar moment of inertia varies as a function of X. So let’s say we take a slice out of that shaft. A pancake, of thickness dx. What does that mean?”

After a long silence, a student: “The polar moment of inertia…”

Me: “WRONG. What does it mean to have a pancake of thickness dx?”

After another long silence: “The maximum shear stress will be…”

Me: “WRONG. A PANCAKE OF THICKNESS dx IS A CREPE.”

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