22 March 2012

Amazing behind-the-back pass!

Have you seen the amazing behind-the-back pass made by Danilo Gallinari?  I analyzed the pass for YAHOO! SPORTS.  Click here for the link to the article by Kristian Dyer.

21 March 2012

Lionel Messi -- Stability and Greatness!

By now the sports world has learned that Lionel Messi became the all-time leading scorer for Futbol Club Barcelona.  Messi earned the record in style with a hat trick last night against Granada.  Click here for an ESPN story and video highlights of Messi's three goals.  There is some great physics behind what Messi does on a football pitch!  All players are, of course, constrained by the laws of physics, but Messi is a fantastic player to watch when trying to understand the crucial role played by physics in goal scoring.  I have no idea how much physics Messi understands, but it is clear watching him that he has assimilated physics principles into his technique.  It is also clear that Messi has great teammates who are often able to get him the ball in what looks to be the perfect place.

Consider the first goal at the 17-minute mark.  On the above video, look at the footage near the 0:10 mark.  Messi was waving for the ball with his right hand just before entering the penalty area.  The ball reached him perfectly at about 5 yards (4.6 m) into the box.  Because Messi was right of the goal, he rotated his body counterclockwise (as seen from above).  When his left boot made contact with the ball, Messi was leaning slightly to the right, thus maintaining stability by ensuring that a net torque did not rotate him toward the ground.  Messi's left foot crossed in front of his body as he struck the ball, but his rightward lean kept him stable.  The ball struck the post on the left side of the goal and ricocheted in for the goal that tied the Barcelona record.

For the goal that set Messi apart from all Barcelona players, go to the 0:31 mark of the video where the game was in the 67th minute (was Messi offside?).  Messi was around 10 yards (9.1 m) from the goal.  Watch what happened when Messi received the ball with his left boot.  To maintain stability while his left leg was raised, Messi leaned back slightly, and you will note that both his arms were raised out from his sides.  By having his arms out, Messi was able to control any possible side-to-side motion that might have resulted from an unbalanced torque while his left boot dealt with the ball.  By moving his arms out, Messi increased his moment of inertia, which increased the torque required to tip him over.  If you freeze the video just right, it almost looks like Messi was doing the crane from Karate Kid, though his arms were not raised as high as Daniel's were (click here if you don't know what I mean).  Messi then booted a slow rainbow kick over the goal keeper, who was only about 3.5 yards (3.2 m) in front of Messi at the time, that sneaked into the left side of the goal.

For the goal at the 86-minute mark that earned Messi the hat trick, go to the 0:55 mark of the video.  Messi received a perfect pass 9 yards (8.2 m) from the goal line and 6 yards (5.5 m) right of the right goal post.  Mess first made contact with the pass with his left boot while his left leg was extended well in front of his body, a necessary move to arrest the motion of the pass.  Again, phenomenal stability was maintained because Messi's right leg was extended well behind his body.  He thus made sure there was not net torque to cause him to slip.  Messi then did his magic by eluding the goal keeper and getting to nearly the deepest part of the rightmost portion of the goal area.  Having rotated his body counterclockwise (as seen from above), Messi was able to gently guide the ball into the goal with his left boot moving in front of his right leg.  Just at the point of striking the ball, you will see Messi's lower legs almost making an X shape with his knees slightly outward.  Once again, complete stability!

There are many great players, past and present, that one may use to learn about the physics of great football.  For me, however, Lionel Messi is the paragon I use to see wonderful physics in the beautiful game.

18 March 2012

Bitter Sweet Basketball -- It's Still Just a Game

There is a very good reason that "fan" is (probably) short for "fanatic" when referring to a sports fan.  We fans are often delusional when it comes to our sports teams.  In some rare instances, that delusion turns violent, leading to tragic results, like the recent Port Said Stadium disaster in Egypt. Most of the time, however, sports delusion manifests itself in a "faith" that our favorite team can, and should, win almost every game it plays.  One definition offered by Webster for "faith" is the firm or unquestioning belief in something for which there is no proof.  Those wonderful italic words make it clear that science is not faith-based.  They also make it clear why we sports fans have too much faith when it comes to our teams.  I number myself among delusional sports fans!

I did not pick Vanderbilt to beat Wisconsin when I filled out my March Madness bracket.  In a quiet, rational moment while contemplating "Vanderbilt" or "Wisconsin," I entered the better team in my bracket.  Of course, pessimism is a part of many sports fans' psyche.  We simultaneously have faith in our team's chances while picking against our team because we actually think that lowering expectations will help us accept a potential loss just a tad better.

Watching yesterday's loss to Wisconsin, I knew that my team was simply not quite as good as the other team.  Still, in those final minutes, I believed that anything could happen and that my Commodores could pull out the win.  Unlike that game Cinderella wins against a better team that they probably could not repeat if the two teams played ten more times, my Vanderbilt Commodores simply lost to a better team in the Wisconsin Badgers.  We had a few more turnovers, and when the game was on the line, they hit a three they had no business hitting and we missed an open look at a three.  Ballgame.  We lost by three.  Sure I was disgusted that we lost.  Sure I wondered "what if?" about a hundred times while replaying the game in my mind in the span of about ten seconds.  But faith came to an end when the proof of which team was better got played out right in front of me.

After a few minutes of anguish, my sensibilities returned.  Hey, no shame in losing to a better team, right?  I suppose my benign delusion was okay for a few minutes -- loving my alma maters is part of what makes my life fun.  Congratulations to Wisconsin for advancing to the Sweet Sixteen.  Congratulations, too, to my Vanderbilt Commodores.  For an alum like me, I'm proud of my team.  We won 25 games this year, plus we get to put a shiny SEC Tournament Champions trophy in our case in Nashville.  A great season!

What's funny is that while the delusional part of my mind that focuses on Vanderbilt was returning to reality, the part of my mind colored cream and crimson was still frantic about Indiana's chances of beating Virginia Commonwealth University.  One gut-wrenching game bled into another!  Indiana shot well during the game, but we turned the ball over so much that I began to wonder if one of our called plays was "step out of bounds!"  There was a stretch in the second half when I simply couldn't believe what I was seeing.  All I could see was my team's mistakes.  It simply wasn't registering in my mind that my team's carelessness was being offset by VCU's protracted shooting drought.  As much screaming as I was doing after each lost IU possession, it was only in the final minute or two that I realized that we actually had a chance to win the game.

Much like Vandy's loss to Wisconsin, the end of the IU win over VCU came down to which team could make a final play.  We hit our open shot; they missed their open shot, which would've won them the game had it fallen.  After their shot missed and all zeroes showed on the game clock, my strongest memory is hearing my older daughter running into another room to tell her mom, "Daddy is jumping up and down in front of the TV!"  In the span of about an hour, I had experienced the low of watching my team come up just short and the high of watching my team squeak out a win it probably shouldn't have gotten.  Such is life for a sports fan!

So Indiana moves on to the Sweet Sixteen for the first time in ten years.  Kentucky is waiting for us.  Kentucky, the #1-overall seed in the tournament.  Kentucky, the team we beat on our floor with the shot of the year (so far).  It's a relatively quiet Sunday morning right now and I know that Indiana has no chance to beat Kentucky next Friday in the Georgia Dome.  Such craziness to think that we can!  Oh, but wait, I feel some good faith-based delusion sinking into my head.  Ten years ago, Indiana was a #5 seed, just one seed worse than this year.  We faced the #1-overall seed that year in the Sweet Sixteen.  We beat Duke by the IU-famous score of 74-73 (think 1987 title game for another great 74-73 win), which got us marching to the title game before losing to Maryland (in a completely unwatchable game, though not as bad as last year's final).  Hey, it can happen again, right?

A little delusion is fun.  Let's not forget, though, that the sports teams we love so much play games.  At the end of the day, it's still just a game.  As crazy as I get watching my teams in tight games, my passion for science is much stronger.  My love for my family and friends is even stronger.  Of the 68 teams to make the Dance, 67 will lose their final game.  The fact that almost all teams in a given sport lose their final game of tournament play means that the overwhelming majority of sports fans are disappointed to some degree once the season ends.  Put sports disappointment in its proper perspective and enjoy all the other wonderful aspects of life.  For me, seeing my younger daughter's excited face this morning when I wished her a happy 6th birthday put all my sports highs and lows where they should be -- way, way down on my priority list.

17 March 2012

100 International Centuries!

My recent sports obsession has been with the NCAA men's basketball tournament -- the Big Dance.  Both my alma maters, Vanderbilt and Indiana, are still alive; both are playing this evening for a shot at the Sweet Sixteen.  Many sports fans in the US, including me, were thrilled last night as Norfolk State and Lehigh pulled off monumental upsets.

Amidst all the basketball excitement, I couldn't help but notice the sports news coming out of the cricket world.  India's great Sachin Tendulkar scored his 100th international century yesterday against Bangladesh.  If you are reading this and know nothing about cricket, take a few minutes and read a story or two online about Tendulkar's achievement.  India has nearly four times the population of the US, meaning there are a lot more people celebrating what Tendulkar has done compared to those of us who live and die with each basket during March Madness.

I was introduced to cricket in my mid 20s.  The aerodynamics of the cricket ball is of great interest to me, but I only began following the sport once the 2011 Cricket World Cup got underway.  India won its second World Cup last summer after beating Sri Lanka.  Working with my colleague, Chin Liyanage, who is from Sri Lanka, and researching with Aakar Verma, an Indian student who came to Lynchburg College last summer to work with me, have given me opportunities to broaden my understanding of cricket.  Whether or not you get into the big numbers in sports, and even if cricket is not so familiar to you, Sachin Tendulkar is a name a fan of sports should know.

Is Sachin Tendulkar the greatest batsman that cricket has ever seen?  I invite those more familiar with cricket's storied history than I am to answer that question either by commenting here or by e-mailing me.

14 March 2012

Amazing trick shot!

While working out at the gym this morning I saw an amazing trick shot on ESPN.  During an Iowa practice, a player wearing number 20, who ESPN tells me is Andrew Brommer (if I have the wrong player, please let me know!), hit a near-full-court backwards shot.  Click here for a YouTube video of the shot.  Once I saw the shot, I had to model it!

By my estimate, the shot went just over 77 feet (nearly 24 m) and took about 2.8 s to get from his hand to the basket.  The trajectory of the shot is shown in the image below (click on the image for a larger view of the graph).

Note that the red dot on the graph represents the basket location.  Note also that the date I use is the upload date for the video (if you know the date of the shot, please let me know!).  The basketball left Brommer's hand at about 44.5 mph (19.9 m/s) at 52° above the horizontal.  The ball reached a maximum height of 38.7 feet (11.8 m) above the court.  Upon entering the basket, the ball's speed was about 29.2 mph (13.0 m/s).

Luckily, someone filmed the shot.  There are lots of fake athletic feats online, many of them are impossible trajectories.  Given that I saw the shot on ESPN this morning, I take the shot to be real.  Certainly a once-in-a-lifetime shot!

11 March 2012


THIS is why I love college sports!  My alma mater, my beloved Vanderbilt Commodores, shocked the college basketball world today with an SEC Tournament Championship win over #1-ranked University of Kentucky.  Click here for the story.  As the only private school and only top-20 academic school in the Southeastern Conference, Vandy has no hope in football and just a tad more hope than that in basketball.  We make a bowl game in football once in a blue moon, and, like this past season, it's usually because 6-6 teams are allowed to play in bowl games (crazy!).  We make an occasional run to a Sweet 16 in basketball, and that's considered a great coda to a good season.  Athletic expectations at my alma mater are not through the roof.  That is why today is so sweet.

We had to beat a less-than-stellar Ole Miss team in a hard-to-watch game (we missed TWENTY three-point shots!) to make the SEC Tournament final for the first time in 61 years.  We won the final in 1951, which is our only other SEC Tournament championship.  My parents were a year old in 1951, so it's easy to understand why a Vandy alumnus like me is raising a pint in celebration right now (I'll think about physics later!).

What makes today especially sweet is that we beat Kentucky, the undisputed top-ranked team in the land.  They had to miss TWENTY-TWO three-point shots today so that we could win by 7 points.  Kentucky is always the team-to-beat in the SEC.  They have the most national titles (7), the most SEC regular-season titles (47), and the most SEC Tournament titles (27) of any SEC team.

Vandy ended Kentucky's 24-game winning streak today.  The last and only other team to beat Kentucky this season?  My Indiana Hoosiers on 10 December 2011!

01 March 2012

Henri Lansbury's Amazing Cross-Cum Goal!

While I was celebrating Clint Dempsey's goal that gave the US its first-ever win against Italy, I noticed an even more impressive goal.  Playing for England's Under-21s, Henri Lansbury hit a spectacular cross-cum-shot from the left wing that curled into the upper-right portion of the goal while the Belgium goalkeeper Koen Casteels was futilely leaping after it.  YouTube video of the goal may be seen here.  I absolutely had to model that kick!

Lansbury's phenomenal goal took place in Riverside Stadium, which is located in Middlesbrough, England.  The pitch in that football stadium measures 115 yards by 75 yards (105 m by 69 m).  I estimate that Lansbury took the shot from nearly 28 yards (26 m) from the goal line and almost 30 yards (27 m) left of the center of the pitch.  His shot traveled approximately 40 yards (37 m) to the goal.  After I timed the shot several times, I estimate a time of flight of 2 s.

Incorporating drag and Magnus forces on the football, I determined the launch parameters needed to get the football into the upper-right portion of the goal.  The graph below shows the three-dimensional trajectory from my model of Lansbury's shot (click on the image for a larger view of the graph).

The red curve shows Lansbury's shot.  My calculated launch speed is 59.8 mph (26.8 m/s).  The blue curve in the above graph shows what the trajectory would have looked like had the football not been spinning, meaning no Magnus force.  Reaching essentially the same height, the ending point of the blue curve is about 9.7 yards (8.9 m) away from the ending point of the red curve and well to the right of the goal.  Lansbury clearly needed spin on the football to make the highlight reel!