Pencil Gauge: The Physics InsideThis clever tool works without any batteries or circuits.
From the show
Why it looks like thatDiscover the simple genius behind the pencil-style tire gauge. This common tool uses a purely mechanical system to measure air pressure with surprising accuracy. When pressed onto a valve, air pushes a small piston against a calibrated spring. This action extends a marked rod, which stays in place due to friction, allowing you to read the PSI even after removing the gauge. It's a perfect example of effective, battery-free engineering.
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