The Premise
The Set Up
The set up for this model is really cheap and easy so it's possible to use as a demo in the front of the class or a manipulative for each group in the room. Basically all you need is two empty egg cartons. I like one of them to be an 18-egg carton because it's wider and does a nice job of representing the table or the floor but this would work with two 6-egg cartons as well
The Model
When the object is at rest, the microscopic features of both surfaces "settle in" to each other kind of like the nesting of the two egg cartons. Overcoming this microscopic interlocking requires a certain amount of force but once the object has "risen above the grooves", as long as it keeps moving it is able to skirt along with less resistance than that initial scenario. This is analogous to static and dynamic/kinetic friction and is a nice conceptual starting point before collecting data and quantifying this properties with numbers.
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