Hooke's Law: a comparison of the rubber band and a spring

 

Data Collection by Myriam & Lesley

We know that Hookean and non-Hookean materials behave differently when stretched.  I found it so interesting though to see it so clearly when comparing the two lines above.  You may notice the nicely paced data points that resemble the elongation of the spring (the blue line).  Compare it to the points close to the red regression line (by the way, Desmos is the best quick regression tool ever); those points resemble the rubber band data.  Notice those clusters of three points.  The inner structure of the rubber is breaking right in front of us.  It is like, stretch - stretch - stretch... and then break, and elongation.  And one more time the same thing.  And one more time, the same pattern.  Very cool.  

Thank you, Myriam and Lesley.

A Nice Surprise

I like to think that I know all the time who is doing what in the lab.  Today, however, I did not notice who surprised me with a little gift.  When students left, I found it on my bag:

The first thought was, "How come?"  How come I did not notice?  Anyway, whether I noticed it or not, this is a very, very nice surprise.  Thank you, Student!  This balancing toy bird, supported at its beak, will serve as a cool example of the center of mass and torque equilibrium.

Thanks a million!