Every engineer has a first moment — the demonstration that flipped a switch. A catapult made of popsicle sticks. A soda can that holds your whole weight until you tap it. The reason a kid who’d never thought about it walks out thinking I could do that. This is that moment, made of two toys. No prerequisites. No fear. Just the first time the math does something you can feel — and the first time it lies to you, so you learn to check.
Hit The Catapult and you’ll meet the most useful lie in all of engineering: that air doesn’t exist. Hit The Can and you’ll find out that a wall thinner than your fingernail can hold a couple hundred pounds — right up until it can’t. Two tabs, two switches flipped.
Ray Ray is a homage to a real civil-engineering professor in West Tennessee — a 2021 University of Tennessee President’s Award honoree in the Educate category — recognized for exactly the things written into Ray Ray above: building state-of-the-art courses and constantly updating them, and making it his mission to visit middle and high schools across the region to show students what a career in STEM can offer. (UT Martin News.)
The teachers in this universe are veils for real people who mattered. This one mattered to the builder. Some of you will know exactly who.
Day one of physics, and day one of engineering, we tell you the same lie: air doesn’t exist. It makes the math clean and it makes 45° the magic angle for maximum range. So launch a light foam ball and a heavier hacky sack and guess which flies farther. Then flip the air switch and watch the lie cost you.
With air off, the lighter projectile always wins — same launch energy gives a lighter object more speed, so it flies farther, and 45° is king. With air on, the featherweight foam ball is all surface and no momentum: drag eats it alive and it falls out of the sky, while the denser hacky sack sails past it. The textbook wasn’t wrong — it was simplified. Knowing exactly which simplifications you’re standing on is the entire job.
A soda can’s wall is thinner than a sheet of paper, and standing on end it will hold a stack of books — a couple hundred pounds — like a little steel column. Then it buckles, and buckling is instant and total. Stack weight with the slider. Tap the side. And try it again with the can full.
An empty can is a thin shell: huge strength in pure compression, but a tiny dent or nudge collapses it far below its theoretical load — real cans buckle at roughly a tenth of the stress the metal could take. A sealed full can is pressurized (the CO₂ pushes ~35–50 psi outward), which pulls the walls tight and lets it carry much more — you can’t even dent it with a tap. But push a pressurized can past its limit and it doesn’t crumple quietly… it ruptures. Two different failures: a column that buckles, and a pressure vessel that bursts.
🐧 NULL watched a man drive two hours to set a brick on a paper bridge in a gym, and watched one kid in the back row sit up straight. NULL said nothing. NULL understood that this is where every other lab begins.
The catapult uses real projectile motion — the textbook (no-air) case really does favor the lighter projectile and a 45° launch, and quadratic air drag really does punish a light, high-surface object far more than a dense one. Masses, drag, and launch energy are representative, tuned so the intuition-flip is visible; it’s a teaching model, not a ballistics solver.
The can is grounded in real numbers. Empty aluminum beverage cans are extraordinarily imperfection-sensitive — they buckle at only about a tenth of the stress the aluminum could theoretically carry, which is why a tiny dent is catastrophic (Dues, “Soda Can Mythbusting,” Technology Interface, 2006). A sealed, unopened can is internally pressurized to roughly 35–50 psi by dissolved CO₂ (“Determining the Pressure inside an Unopened Carbonated Beverage,” J. Chem. Educ.; Physics Factbook), which stabilizes the thin shell and raises the load it can carry. The exact pound figures here are illustrative.
The pedagogy: the first thing you teach a young engineer is a simplification — and the second thing is what it costs. Built to teach, not to scare.