Wednesday, January 4, 2012

Football physics

What best way to start off the 2012 than to write about 2 things I like: Science + Football. You may not think that there's much correlation between the two, but Science is a-brimming on that 120-yard field, and every football Sunday can be a teaching opportunity.  A throw, a punt, or a field goal kick are perfect examples of parabolic paths, as gravity acts on the ball pulling it to the ground.  For my child, the future looks bright indeed, at least in Physics... and in football.but time is running short, and football season is coming to a close. So enjoy the bowls and the playoffs, and here's to hoping for another great "learning" season beginning in Fall 2012!
When I freshly hopped off the boat plane, I knew absolutely nothing about this sport.  The very first time I watched the game on TV was memorable because it was a) the first time I had Entemann's donut, and b) I was so traumatized by all the hits and sacks that I had to watch peeping through my fingers.  It reminded me of the old Batman series with balloon captions "Ka-pow!" "Bam!" and "Zing!"  My then-boyfriend and now-husband would pry my hands open and laugh as I cringed in a corner, holding on to my donut for dear life. I couldn't understand how anyone would survive such a pile up. And over what? An odd-shaped ball! (I learned about the multi-million dollar salaries later.) 
Needless to say, I feel differently now.  Somewhere, somehow, something changed. I saw the leaps, bounces, and tackles as graceful choreography.  If I knew how to play the violin, I would provide glorious background music during replays and at key moments.  Caught the ball with two toes inside the line?  Let me play "Chariots of Fire" for you!  Down by seven with 29 seconds remaining in the 4th quarter? Here's my string rendition of “No Surrender."
Like a good student, first came the questions.  Why the odd-shaped ball?  How can the place kicker put a 56-yarder inside the uprights? How does anyone stop a 250-lb running back moving at full speed? Why don't their necks ever snap? Why is Tom Brady so good looking?  But I digress.  Then came the observations, and I began watching this favorite American game through rose colored lab-goggles.
How about you?  Ever wondered about the football's ellipsoid shape? That's a prolate spheroid to us nerds or an egg shape of sort to the rest of you.  Before football, the only ball shape I knew was the spherical kind. But when I watch this game, I'm in awe at how this unique shape renders the ball more aerodynamic, easier to throw and catch, and less predictable in bouncing, which makes for an exciting game.  A well thrown ball rotates in its long axis of symmetry in flight, and the quarterback in motion or standing in the pocket will have to apply a different vector - a combination of speed and direction - to accurately send the ball to the receiver, especially to hit a running target.  And then, there’s air drag to think of.  Air drag depends on weather and altitude. So the same ball thrown will travel farther in mile-high Denver than it will in sea-level Meadowlands.  Is that why the NY Jets lost to the Denver Broncos?  Maybe every coach needs a physicist on their staff!
Football also offers wonderful examples of Newton's 1st, 2nd, and 3rd laws of motion. Newton's first law is the law of inertia: A running back in motion remains in motion until flattened by Desmond Bishop. I always think of Newton's second law, Force = mass x acceleration, whenever I see a running back about to cross the goal line for a touchdown and his O-line bumps him from behind (those centers have lots of mass!) giving that extra "Oomph" to earn the few inches against a resisting defensive line.  As for Newton's third, “for every action, there is an equal but opposite reaction,” just look at the faces of Redskins fans every time Rex Grossman throws an interception.  Ok, maybe not quite the scientific example you were looking for.
Then there's the difference between elastic and inelastic collisions. Whoever has more momentum on contact pushes the other backward or forward in an elastic collision. But if the guard holds onto a pass rusher, that's inelastic collision, with a ten yard penalty.  To hold steady while blocking, linemen crouch low, which keeps their center of mass close to the ground, rendering them immovable as boulders.
There’s more to think about, like how helmets act in the distribution of force to protect the players, and the how the different coefficients of friction of turfs affects the run game, but there's little time left and football season is coming to a close. So enjoy the bowls and playoff games, and here's to hoping for another great season of "learning" in Fall 2012. Cheers!

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