Deflategate: Classroom Thermophysics Investigation via Simultaneous Pressure and Temperature Measurement Inside a Football

摘要

On January 18, 2015 the new England Patriots defeated the Indianapolis Colts 45 to 7 in the American Football Conference Championship Game. Accusations were levied against the Patriots that game footballs had been intentionally deflated to make them easier to handle. Cheating allegations induced months of intense media coverage and earned the moniker "Deflategate". After investigation and trial, the Patriots were censured. However, they never admitted guilt, leaving the facts unresolved. Instead of tampering, might observed football deflation have an underlying alternative thermophysical explanation? For locker-room-inflated (～296 K) game footballs played in cold Foxboro stadium (～283 K), Gay-Lussac's Law predicts a 4.4% pressure drop, corresponding to 4.1 kPa below full ball inflation. Can thermophysics combined with non-idealities such as air leakage explain Deflatefate? The incident provides foundation for a hands-on experimental high school chemistry laboratory activity that relates this professional football controversy to relevant aerospace engineering thermophysical concepts. By simultaneously measuring the pressure and temperature inside a football inflated at one temperature and played with at a different temperature, students learned and applied analysis techniques to determine for themselves what really caused the Patriots ball to deflate 13.8 kPa below the bottom acceptable National Football League game football pressure. This paper describes the methods, procedure, analyses, and results of our classroom experiment to enable other educators to adopt the Deflategate activity for their classes.