Originally Posted by Skidude72
Perfect post for the Iconoclastic Automatic Turn thread!
Oldschool - seriously..... By your "logic" the energy stored in my hallway floor by now would be enough for the whole neighbourhood to blow up...heck my shoes would be ticking time bombs....common on man. Placing weight on something does not result in "stored energy", just an equal and opposing force...which disappears the moment you remove the weight. There is no "energy" in a rock just sitting on the ground. That doesnt change if you put skis under it....no matter what the 16 year old pimply faced ski salesman at the ski store told you.
Skidude72, seriously, think it through.
Lift the rock. How much energy do you need? If the is no energy in the rock, why does it have wt?
Deflection in the floor would be in direct relation to your wt which would translate into a bending moment of the floor where you are standing. Deflection = stored energy while it is applied. Simple stuff actually.
Ref: Mechanics of Materials 2nd Ed 1978
specifically Chap 6 Relationship between shear and bending moments.
There is another book I'd like to reference but it is still buried since the move.
Take a 2x6 and place each end on a block.
Stand in the middle of the 2x6.
Does it bend? Of course. This is a bending moment. This bending moment is stored energy as long as the 2x4 is bent (load applied by you standing on it). The drawing is what is happening.
Your wt is counter acted vertically at the 2 blocks. The bending moment (which is another but more descriptive engineering term for torque referenced to the load applied) is the force required to bend the 2x6.
This is simple engineering and physics. Well not so simple as this is actually 1st semester course in university, just to convey the understanding of the concept. Get past this one the rest is easier but not simple.
I don't mind the criticism, just show me the faulty math/engineering if you are going to do so. I don't mind standing corrected if I've made a mistake.
I'm sorry if I can't be clear enough to help you understand, as most students (myself included) took/take a lot longer than a few little examples to grasp this concept.
Sorry jbharstad and Bud, I was trying to give a fair and honest description for my statement and have lead the thread astray. jbharstad, please show a video, I honestly want to understand what you are saying. I think it may just be terminology that is tripping everyone up.
Anyone else on this topic, please PM me and I'll answer fairly to help with what was stated, not to take away from this thread.