Recent content by Ssantos

Thanks again. I think I more or less see what I was doing wrong (or thinking wrong). I will think a bit more about it until I get a better understanding. Thank you though!

One last thing arguing in favour of what I said above. If you hang a weight on a bar the work that goes into increasing the kinetic energy would set vibrations on the bar. And if the bar was to be in a vacumm, so no damping ocurred, and provided the elastic limit is not surpased, so no energy is...

Thank again Andy. Well, the fact is that the definition of work is Force dot product differential of displacement. The Force is, if not applied slowly and modifying it, just what you hold onto the bar, namely F or the whole load. However, if applied fast, as it would normally be if you put a...

Finally, Equation 4 above is, again, the equation obtained for a thin element not accounting for the slow deformation. But still I see it as a very tricky detail and I don't know to what extent it's just an experimental fact.

Thanks Andy. It just looks very tricky since they obatin the work for an element from: W=Integral (Pds) where first they use the fact that P=f(s) from Hooke's law, thus: P=ks Then they integrate and get the usual W=1/2ks^2. The key here is the fact that insetad of leaving the...

I have a problem understanding what is going wrong with a simple derivation for strain energy. Problem: Assume a prismatic bar of length L where the elastic region is assumed. If it is hanging vertically its own weight produces some strain. If all the work goes into strain energy the...