30 June 2012

Stage 1 Prediction

Eric is without power; this is his brother-in-law typing.  He has just phoned me with his stage 1 prediction.  

4h 49'18"  (prediction)

29 June 2012

It's Tour de France time!

One of my favorite times of the year is at this very moment.  We are but a single day away from the start of the Tour de France.  This year's race begins with a Prologue stage in the Belgian city of Liège.  The 6.4-km (4.0-mile) individual time trail will whet our appetites for the 3496.9 km (2172.9 miles) that will be completed by the time cyclists hit the Champs-Élysées on Sunday, 22 July.

I wrote a guest post for The Johns Hopkins University Press blog that concerns my Tour de France modeling.  Click here for the direct link to the post.  As I state there, I plan to stick my neck out again this year and offer predictions for each stage's winning time.  My student, Brian Ramsey, and I incorporate real stage data into a model that employs the unalterable laws of physics and published human-performance research to come up with our predictions (see chapter 4 of my book).  We never know in advance, of course, if there will be poor weather, crashes, or some other impediment to great racing.  We do the best science we can, and have a lot of fun in the process.  So, without further ado, below is our prediction for this year's Prologue.
  • Prologue:  7' 35" (prediction)
My best guess is that a cyclist will beat our time, but that's what makes this so enjoyable!

28 June 2012

Balotelli Sends Italy to the Euro 2012 Final!

Mario Balotelli was sensational for Italy as The Blues knocked out a German team that I thought would make the final of Euro 2012.  The people in Warsaw's National Stadium got to see one of the world's best on display as Balotelli scored both of Italy's goals in the 2-1 win.

Click here for ESPN's GameCast of the match.  Balotelli's first goal came in the 20th minute as he received a perfect cross from Antonio Cassano.  Watch the replay of the goal and you'll see Cassano on the left side of the penalty area.  He kicked the ball with his left boot, and the ball was spinning clockwise (as seen from above).  There was so much spin on the ball that the Magnus force pushed it left to right (as seen from Cassano's viewpoint).  By the time the ball reached Balotelli's head, which was centered about 5 m (5.5 yards) from the goal, the ball had a velocity component toward Balotelli.  It was the perfect cross into the box and Balotelli nailed it.

Balotelli's second goal came in the 36th minute as the German defense let him slip through for a shot at the goal about 16.5 m (18 yards) out.  This goal was pure power.  Click on the image below for a larger view of the trajectory of Balotelli's goal.

The red curve shows the actual trajectory; the blue curve shows what the trajectory would have looked like had there been no spin on the ball.  Balotelli smashed the ball with his right boot with a right-to-left motion as he drove his foot into the ball.  That gave the ball a clockwise (as seen from above) rotation that caused the ball to veer toward the upper right corner of the goal. Balotelli thus kicked a "screwball" in the baseball sense (click here for my post from six days ago on that topic).

I estimate that Balotelli's shot took about 0.544 seconds (after averaging several viewings of the goal) to reach the goal plane.  The ball's initial speed was 32.7 m/s (73.1 mph).  Couple that enormous speed with a screwball effect and Manuel Neuer, Germany's goal keeper, had no chance whatsoever to prevent the goal.  All Neuer could do was what the rest of us did -- watch with awe the power and beauty of Mario Balotelli's game-winning shot.

24 June 2012

Italy moves on!

After 90 minutes of scoreless football in Kiev, England and Italy played two additional 15-minute periods of scoreless football.  Italy had possession for 68% of those two hours, and had taken 36 shots (8 on goal) to England's 9 shots (1 on goal).  Italy passed better, attacked better, and looked much crisper than England.  Despite looking so much better than England, Italy simply could not score.  England's goal keeper, Joe Hart, played great, as did the Three Lions' defense.  Two hours of dominant play got thrown out for Italy as the match moved to penalty kicks.

When Riccardo Montolivo missed Italy's second penalty attempt, I thought England had lucked out the win.  Instead, Ashley Long's penalty kick for England hit the crossbar.  Gianluigi Buffon made the sole goal-keeper save of the penalty-kick session when he stopped England's fourth kick by Ashley Cole.  Italy had the victory with a 4-2 penalty kick score.

Imagine how difficult it is for a goal keeper during penalty kicks.  The ball is kicked from just 11 meters (12 yards) out.  A hard-kicked ball may leave the kicker's boot at roughly 30 m/s (67 mph), though penalty kickers may opt to bring speed down to improve accuracy.  Andrea Pirlo's penalty kick for Italy was quite slow and down the middle, which fooled Joe Hart.  For all the advanced study of penalty-kick tendencies, luck plays a major role.  A ball kicked at nearly 30 m/s will reach one of the upper corners of the goal in about 0.4 seconds.  That's the same time it takes for a Major-League fastball to reach home plate after the pitcher lets go of it.  Studies in human reaction time suggest that eye-hand reactions take place on the order of 0.20 seconds, whereas eye-leg reactions need nearly twice that time.  In short, if a goal keeper stands in the center of the goal and simply reacts to a penalty kick, there is no way to stop the kick.  The goal keeper must guess ahead of time.  Gianluigi Buffon made a great guess on Ashley Long's kick.

Italy moves on to face Germany in the semifinals.  Italy will need to finish much better against the Germans compared to how they did against England.

22 June 2012

Germany's Screwball Goal ...

Germany was much too powerful for Greece in today's Euro 2012 quarterfinal action.  Earning a 4-2 victory in Gdańsk (Poland), Germany moves on to the semifinal round against the winner of Sunday's England versus Italy match.

The goal I most enjoyed in Germany's win was the first one.  Click here for ESPN's GameCast of the match.  Click on The Team's first goal and enjoy Philipp Lahm's smash from about 22 m (24 yards) out.  Go to the 0:47 mark in the video for a great slow-motion look at Lahm's goal.  Note that Lahm hit the ball with his right boot.  Note, also, that Lahm's right leg moved powerfully across his body, meaning that he was twisting counterclockwise (as seen from above).  His twist was so strong that he lost his balance upon returning to the pitch after his brief moment in the air.  That kicking motion gave the ball a clockwise (as seen from above) component to the spin.  The video shows quite well that the ball tailed away from the Greek goal keeper, Michail Sifakis, in a left-to-right manner (as seen by Lahm) as it slammed into the upper right portion of the goal.  Without the rotation and the curve due to the Magnus force, the goal keeper would have blocked the ball (Sifakis managed to just get his left pinkie on the ball).

If a right-handed baseball pitcher throws the ball with a component of spin that is clockwise (as seen from above), we call that pitch a screwball.  Not too many pitchers throw that pitch because it is hard on the arm.  Old timers like Christy Mathewson and Carl Hubbell were famous for throwing the "fadeaway" or screwball.  From my youth, I recall Fernando Valenzuela lighting up Major League Baseball in 1981 with a look to the sky before throwing his screwball.  Today's pitchers rely more on a circle change because it is much easier to throw compared to a screwball.  Anyway, a screwball moves from left to right (as seen by the pitcher) for a right-handed pitcher.  That is the same type of motion that Sifakis had to deal with from Lahm's great kick.

The Magnus force makes for some wonderful trajectories!

19 June 2012

Ukraine's no goal ...

I am happy to see England move on to the quarterfinals of Euro 2012, but today's win over Ukraine shows why replay needs to be a part of professional football.  The image below (cropped from televised replay) shows that Marko Devic's shot was clearly a goal, despite not being called a goal.  Click on the image for a larger size.
The referee standing along the goal line did not call this a goal.  I really can't blame the referee given how fast the above play moved in real time.  There may have been poetic justice in the "no goal" call because Ukraine was offside earlier in the attack, but that doesn't change the fact that replay is needed to decide calls like the one shown above.  Goal-line technology is here and is easy to implement.  The above image could have been created seconds after the play and a decision could have been made within a minute of stopping play.  There aren't that many goals in a typical football game, and there certainly aren't that many controversial goals.  In a given tournament, there are, what, one or two (at most) controversial goals that could benefit from replay?

Join the 21st century and get the call right!

17 June 2012

Portugal and Germany Dominate Group B!

Father's Day allowed me the opportunity to take in a little world-class football today.  The quality of play by the Portuguese and Germans did not let me down.  As much as I love the physics associated with football aerodynamics, what dropped my jaw today was the physics of the ball on the pitch.

The Navigators are lucky to have Cristiano Ronaldo on their club.  Ronaldo is fortunate to have teammates with the incredible skill to put the ball in the just the right place for him to shine.  Click here for the ESPN GameCast of Portugal's 2-1 win over Netherlands in Kharkiv.  Joao Pereira set up Ronaldo's first goal in the 28th minute with a fantastic ball through the Dutch defense.  About 30 meters (33 yards) from the goal, Pereira sent the ball off the outer portion of his right boot to meet Ronaldo nearly 14 meters (15 yards) from the goal.  The timing was perfect as the ball met Ronaldo in stride.

Ronaldo's second goal came in the 74th minute after an even more impressive setup.  Nani was racing down the right side of the pitch and kicked the ball about 27 meters (30 yards) from the goal line along the right boundary line of the penalty area.  Nani booted the ball with his right foot.  Note the counterclockwise rotation (as seen from above) Nani gave the ball.  That rotation caused the ball to curve to the left as it rolled along the ground, reaching Ronaldo in stride about 11 meters (12 yards) left of center of the goal.  The friction force from the pitch on the ball was responsible for the force that pushed Nani's ball to the left.  As the ball reached Ronaldo, it was literally moving sideways into Ronaldo's left boot.  A truly spectacular pass from Nani!  I urge you to watch the video on the ESPN GameCast page, especially the winning goal for Portugal.

Click here for the ESPN GameCast of Germany's 2-1 win over Denmark in Lviv.  Take a look at The Team's opening goal in the 19th minute by Lukas Podolski.  The flick from Mario Gomez to redirect the ball to Podolski was a thing of beauty.  The Germans showed how teamwork and precision passing led to a goal.  Human reaction time is at least 0.2 seconds or so.  Once Gomez flicked the ball and Podolski was in place for the smash into the net, The Olsen Gang could not react fast enough -- no team could.

Portugal and Germany move on to the quarterfinals of the Euro 2012.  The Czech Republic (against Portugal) and Greece (against Germany) will have to defend great movement of the ball on the pitch!

15 June 2012

Three Goals for Three Lions!

England had a spectacular win against Sweden today in Group D action of the Euro 2012.  Olympic Stadium in Kiev was the venue for the exciting match.  The Blue-Yellow is guaranteed to finish in the bottom two of Group D.  To see all the goals in England's 3-2 win, click here for ESPN's GameCast page.  I found delightful physics in all three goals.
  • Andrew Carroll opened scoring in the match in the 23rd minute.  Steven Gerrard's cross was amazing!  From about 36 meters (39 yards) down the right side of the pitch, Gerrard sent a perfect cross to Carroll, who was about 11 meters (12 yards) from the center of the goal.  Go to the one-minute mark of the short video showing the goal.  Carroll is in the air in slow motion executing a wonderful header.  Once off the ground, Carroll's angular momentum is conserved.  Note how his head whips to his left while his right arm swings behind his back.  Those two rotations are in opposite directions.  Carroll's left leg rotates toward the right side of his body.  All of those rotations are such that Carroll's angular momentum in the air matches the angular momentum he had when he left the ground.  Watch Carroll while in the air!  He is poetry in motion after receiving Gerrard's wondrous cross.
  • Theo Walcott drew England even in the 64th minute, just about five minutes after Sweden had taken a 2-1 lead.  About 24 meters (26 yards) out, Walcott send a scorching shot through a crowd of players.  Go to the 43-second point in the video for the slow-motion replay.  Watch the flight of the Adidas Tango 12 ball.  The is a component of spin that is counterclockwise (as seen from above).  There is also a topspin component to the ball's spin.  That topspin component helps the ball dip into the goal.  Walcott had to kick the ball high enough to clear the wall of defenders, and he needed just enough topspin for the ball to have a downward deflection from the Magnus force.  A great kick!
  • The winner for England was simply mind-boggling.  In the 78th minute, Theo Walcott fired the ball from the right side of the box and connected with Danny Welbeck.  Go to the 55-second point in the video for slow motion of Welbeck's goal.  You will see Welbeck spinning clockwise (as seen from above) as he receives the ball on the heel of his right boot.  Welbeck's back was to the goal!  His rotation continued after he kicked the ball so that he could witness his winning goal.  Imagine the incredible control and balance needed to do what Welbeck did.  Though he fell to the pitch after rotating toward the goal, he was in complete control as the ball reached his right heel.  Stability physics tells us that strong cores are needed to maintain balance and control during top athletic competition.  Keep doing those sit-ups!
England will be back in Donetsk next Tuesday to take on Ukraine.  Lots more football and physics to be seen!

11 June 2012

Gerrard to Lescott!

Given their injuries and the suspension of Wayne Rooney, England was fortunate to escape with a 1-1 draw against France in today's Group D match-up in the 2012 UEFA European Football Championship.  The players looked to be taxed in the evening heat of Donbass Arena in Donetsk, Ukraine.

I loved Steven Gerrard's long kick to Joleon Lescott in the 30th minute.  Lescott received the ball perfectly just inside the 6-yard box, nearly centered by the plane of the goal.  Click here for video highlights and go to the 0:46 point in the video.  Below is my model of Gerrard's kick (click on the graph for a larger image).
The red curve is Gerrard's kick; the blue curve is what Gerrard's kick would have looked like had the ball not possessed counterclockwise spin (as seen from above).  There is no goal without the lovely Magnus force curving the ball towards Lescott!  I estimated that the time of flight of the ball was 1.73 seconds and that it left Gerrard's boot at about 25 m/s (90 km/hr or 56 mph).  Lescott was able to sneak past the French defense for the header that put England on top, a lead they would hold for only about 9 minutes before Samir Nasri tied the score with a great shot left of goal just outside the box as England's defenders looked a little lost.

England and France play again in four days.  The Three Lions will take on Sweden; Les Bleus will face Ukraine.

05 June 2012

Grand Tour Modeling

A short video describing the Grand Tour modeling that I have been working on with my research student, Brian Ramsey, appears on my college's home page.  Click here for the Lynchburg College home page or here for a direct link to the video on YouTube.  Many more details behind Grand Tour modeling appear in Chapter 4 of my book (click on cover image on the right).