The Science of Solids

Posted by Greg MacDonald on

 I've been working on a revised set of Safer Geography Activity (Command) Cards this past few days.  One goal that I had was to ensure that wherever possible, the "Explanation" really explained, using scientific principles.  That goal sent me off delving into physics from time to time.  

As a future objective I plan to create a second set of these cards for older children, and I want this first set to serve as a scientific foundation for some of the directions I'll be taking there.

Here's what I came up with for Solids Can Be Rigid, Elastic or Plastic:

The force that binds the particles of a solid to one another differs according to the nature of those particles.  Solids resist changing their shape if the force applied is insufficient to overcome the force that binds their particles together (the solid’s yield strength).  We say that the solid is rigid in this case. 

If additional force (but less than the solid’s yield strength) is applied, then the solid deforms, but returns to its original shape when the force is removed. Its particles are temporarily displaced. The solid is then said to be elastic. 

When a force greater than the solid’s yield strength is applied, some of the solid’s particles are permanently displaced, and the shape of the solid is altered permanently.  We say that this solid is plastic.
The new set of Geography cards is ready to go.  I'll have a revised set of Biology cards done soon, then Music, and then I want to take a look at Geometry cards, before moving on to that second set of Geography cards.
© Greg MacDonald 2019

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