Protect the fine china!

One of the well known uses of Newton's First Law of Motion is the age-old trick of pulling a tablecloth from under a dinner setting. To start thinking about the ideas behind forces, like those we will see in bridges later this week, the students examined the tablecloth trick in a few YouTube videos.

As seen in the video, the tablecloth's motion does not interrupt the inertia of the table setting.  This follows Newton's First Law where objects at rest will stay at rest. But that begs the question, "why?" In class we explained and explored the idea of friction and the role it would would have on china and glassware. The more friction force, the more likely that the objects would crash to the ground.

We also started looking at the formulas derived by Isaac Newton to describe force and its relationship to mas and acceleration. We know that objects that are large would require a large amount of force to change their motion or inertia. This is just like we saw in the video! The friction force of the tablecloth is not enough force to change the inertia of the table setting. Newton's idea of force will be important as we think about the structures found in bridges and the engineering behind opposing forces.

Update:

Homework:

Due Thursday: F6 Homework: Understanding Forces!
Bridge Building begins this week!