Saturday, March 20, 2021

RT;DL Physics in the Fountain of Fizz

The Diet Coke Mentos geyser made a big splash in popular media before social media was a big thing. I was keen to incorporate it into my curriculum, but needed a content-based hook. Mythbusters (among others) focused on the chemistry of the spectacle. That was entirely cromulent: it's the engine that drives the demonstration. 

But I teach physics. And there's plenty of physics to exploit. Between the beginning and end of the eruption, some quantity of mass is ejected. Mass flow rate? Check. The fizz emerges from the bottle with some speed and reaches some altitude above the launch point. Energy conservation? Check. Determination of muzzle speed from maximum height? Check. Total energy dissipation approximation? Check. Power approximation? Check.

My school is a 1960s-era low-slung, sprawling campus. Determining the maximum height of the eruption is non-trivial. Most buildings top out at about three meters. We do have an accessible tall (~6 m) wall made of cinder blocks as part of our gymnasium. So that's what we settled on.

Initial mass is measured. Video is captured. Final mass is measured. The video is analyzed. Calculations are made.

Fountain of Fizz Student Document - Google Docs copy link

Fountain of Fizz Observations - HTML Export | Movie Export

Media links are included in the student document. The movie export is included for use on devices that struggle with the HTML export.

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