Hands-On Physics Day 2: From Model to Full Scale

Today we revisited our question: How many kids does it take to balance against an adult on a teeter-totter? The question still felt a little vague: which kids? which adult? which teeter-totter?

To help us clarify our question, and maybe reveal some issues we hadn't considered, we quickly built a model.

Kaia, Nathan, Hugo and Lux make a model with only four pieces of scrap.

The model suggested something curious: did Lux really weigh the same as Josh? 

Mass of Lux = Mass of Josh ??? 

We quickly realized that distance from the fulcrum--radius--had something to do with how the teeter-totter behaved. Specifically, the two teeterers could always adjust their distance-from-fulcrum to bring the teeter totter--even if one weighed more than double the other! 

Realizing what an interesting variable radius might be, we set to work on a 16-foot teeter-totter. 

Nathan, Trent and Hugo build the fulcrum for the second (bigger) iteration.
Isabella, Kaia and Lincoln lay out the platform.
Lux takes a break--sort of.
What is it like to be BOTH masses on the teeter-totter? Lincoln on the balance board. 
Physics (Fall 2013)Sean Murray