what changes in the structure of an object that allows something to permanently bend (i.e folding paper)
In: Physics
Civil engineer here. Besides what’s happening on the molecular and cellulose level, there is also something called Young’s Modulus, which is a ratio of the stress exerted on a material (in terms of force, such as Newtons or lb/ft^2 or kips) vs the strain (change in L or A per original dimensions). All solid materials have this characteristic. For paper, it is very, very, very low, so that humans can rip it easily or whatever. When you bend paper slightly, it will go back into place. This is the plasticity index, and it indicates the threshold before which the material will return to its original form. Again, paper’s super weak, so it’s practically nonexistent, but steel works the exact same way just with much stronger molecular and physical bonds. Upon surpassing the plasticity index, the material can no longer return to its original form. It is therefore “deformed” in whichever position it was put into, and that’s considered a fold. This is a very tangential connection but is nonetheless a phenomena that occurs as a result of the various qualities of paper that make it the way it is, and explains from the physical perspective why creases happen
Edit: forgot about strain
And thanks for the silver!!
Latest Answers