Stressing Out!

Stress and Strain

This week the 8th grade continued their engineering lesson by talking about material strength – an important property in building materials if you want to make something that is able to withstand an earthquake! After a brief discussion of the various ways to stress and strain a material, the students got to see the five types of stress first hand by bending paperclips, squishing foam blocks, balancing books on their heads, bending and pulling on linguini, and examining the light patterns in plastics as seen through polarizing films.

We learned that the same type of stress can have different effects on different types of materials. Similarly, the same material responds differently to different types of stress! For example, the linguini bent and sometimes broke when weight was hung from its center. But when we held a strand of linguini vertically and attached it to a bucket, it was able to hold over 1,000g of weight!

Ask your student what their favorite station was!


Esfuerzo y deformación

Hoy discutimos sobre la resistencia de los materiales; una característica muy importante, en particular en los materiales de construcción si es que deseamos construir algo que sea capaz de soportar un terremoto. Después de una breve discusión sobre las variadas formas de esforzar y deformar materiales, los estudiantes experimentaron al doblar clips de papel, estirar bandas elásticas y examinar los patrones de luz que se generan al mirar el plástico a través de filtros polarizantes.

También aprendimos que al introducir pequeños defectos o impurezas en la estructura cristalina de un material, podemos aumentar la resistencia de éste.  Esta técnica ha sido ampliamente utilizada por los herreros desde la antigüedad.


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