Dear Lord,
Please tell me you don't work in engineering for a living.
You have deflection confused with strain, buckling columns transmitting forces, and strain exceeding shear strength.
Good job on the speed of a falling object and the Kinetic energy formula though.
I won't speak for the Lord, but I'll address your questions myself.
I am a design engineer for a lowly international company. We really don't know what we're doing, but we manage to muddle through it every day. Good work if you can get it.
deflection is a part of strain. Strain being deltaL/L. Stress being a function of strain, therfore, shear strength is a function of strain, mathematically speaking.
I don't know when structural members stopped transmitting force. Must have occurred since I graduated. I'll have to look that up.
BTW, do you still stand by your earlier statement that steel doesn't break?