Thursday, January 29, 2015

Deflate-gate Tested at BHS

Dr. Johnson and his Physics classes wanted to test the science behind deflate-gate, check out the findings below:

It all started with a couple footballs and pressure gauges that I bought at the Sports Authority.  

My students and I tested Bill Belichick’s claim that the balls could have been “worked up” to read a certain PSI before the game and then another PSI after reaching equilibrium with the playing conditions.  
This gave me a chance to practice ideal gas law problems:

The key would be to get the ball hot before taking the initial pressure reading.  The easiest way to do this was with incandescent lamps.

But Bill said that his team did not put the footballs in an oven.  Could the same increase in temperature be achieved by friction.  To find out, I had my students use electric sanders on the balls.  The sanders had scouring pads instead of sandpaper.  No damage was done to the leather.  

After working on the footballs for about 5 (noisy) minutes.  I took initial pressure readings.  Then I put the footballs outside (it was about 20F that day) for 15 minutes.  For the last step, I took the balls back inside and remeasured the pressure.  

Results:  After several trials (with different classes) the heated footballs dropped an average of 2.5 PSI between readings and the rubbed footballs dropped an average of 1.5 PSI.

Conclusion:  Bill Belichick may have been telling the truth.

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