Stress & Strain

Today in class we discussed how materials can experience different types of stress and strain.  We set up a demonstration using uncooked linguini noodles to show different types of stress.  The first demonstration had the noodle experiencing the stress of the weight from a horizontal position and was experiencing flexure and compression.  The noodle snapped after ~150 grams of stress.  The second demonstration showed the noodle being able to withstand nearly 8 lbs of weight when experiencing tension or pulling stress in the vertical position.  

For the activity in this class today, we were looking at the stress threshold of rubber bands.  We measured the change in length of a rubber band after adding different weights to it.  None of our rubber bands reached the critical stress threshold but we talked about how the rubber bands would have snapped if they had too much weight added.  In class we also investigated the concepts of elasticity and plasticity in different building materials.  We looked at how metal and wood have different properties.  

The next time you and your student drive across a bridge or see a large skyscraper, ask them what building material they think it is made of.  How would that structure be affected if it were made from a different material?  Would it be as strong?  Would it be able to withstand harsh weather?  How much weight would it be able to support?