Making Sport of Physics

Brazuca Physics

During the past couple of months, a few colleagues have contacted me about my recent dearth of blog writing.  Though trite to offer, I’ve been busy!  Research work, teaching, and administrative duties have made little time for blog writing.  What got me motivated to write a post today was an invitation from NPR to appear on All Things Considered yesterday.  I was interviewed by Melissa Block about the Brazuca, which is the name of the new World Cup ball that will be employed in this summer’s world tournament in Brazil.  Click here to get to a page where you may listen to my four-minute interview.

In late 2013, I was invited by Takeshi Asai of the University of Tsukuba in Japan to collaborate with him on aerodynamics research of the Brazuca.  Dr Asai and his colleague, Sungchan Hong, supplied me with wind-tunnel data for the Brazuca, as well as wind-tunnel data for the Jabulani, which was used in the 2010 World Cup.  I spent the majority of my winter “break” analyzing data, coding trajectory models, and paper writing — all LOTS of fun and why I LOVE my job!  My colleagues and I came to the conclusion that the Brazuca is a better ball than the Jabulani.  Much of the wild knuckling effects seen in 2010 should be absent this summer.  The key is that despite six panels on the Brazuca compared to eight on the Jabulani, the total seam length on the Brazuca is 68% longer.  That added roughness leads to a drag crisis at a smaller speed, meaning most intermediate-speed and all high-speed kicks should be in the post-critical region where the drag coefficient is essentially uniform.  The Brazuca also shows better stability than the Jabulani due to more uniformity in the surface roughness.  Many more details appear in our paper, which was recently published in the Journal of Sports Engineering and Technology (click here for a link to the paper).

There are only 50 more days before the 2014 World Cup commences.  I’m anxious to see the new ball in action!

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The Biathlon is Cool!

On today’s Winter Olympics and physics radio spot at The Takeaway, I talk about the biathlon.  Click here to get to the page with the “listen” link.  How great is the biathlon, which is gift from Norway?  If you like skiing and shooting, there is no better sport!

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Winter Olympics Radio Links

The Takeaway combined this week’s radio spots into a single download.  They may be accessed here.  There should be a new segment on the biathlon next Monday.

This past Wednesday, I was on NPR‘s All Things Considered.  Most of the conversation concerned ski jumping.  Click here for a brief write-up and a download link for my segment of the show.

It’s fun chatting about the Winter Olympics — so much great physics involved!

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Speed Skating!

On today’s Winter Olympics radio show for The Takeaway, I talk about speed skating.  Click here for the link.  Lots of great physics, including Newton’s laws and angular momentum conservation, dominate the conversation.

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Freestyle Skiing and Ski Jumping

At The Takeaway today, I talk about freestyle skiing and ski jumping.  Click here for the story and a link to the audio from the radio show.  There is fascinating physics as one converts gravitational potential energy into kinetic energy, all the while either fighting the air (drag) or getting help from the air (lift).  What’s great about the ski jump this year is that women finally get to compete in that Olympics event!

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Ski Jumping and Thoughts on Science and Sports

I worked on a piece for the New York Times on ski jumping.  The graphics are great!  Click here for the story.  It’s about time women get to compete for Olympic gold in this event!  There is so much wonderful physics in ski jumping.  The “V” style alone has increased lift by about 30% over the old skies-pointed-forward style.  Look for some birds that spread their feathers while in flight, increasing lift just like the separated skies of a ski jumper.  We may learn a lot from evolution!

I was invited to write a short blog post for the Johns Hopkins University Press.  The topic is science and the Winter Olympics.  Click here for the post.  In no way does understanding some science behind sports diminish the viewing experience.  There is so much beauty in the laws of nature, and I marvel at how human beings continually push the envelope of what’s possible.  The athletes are special, but so are the scientists who design better and better equipment, craft more sophisticated training regimen, and use modeling to find seemingly small ways that improve performance.  For events timed to the nearest thousandth of a second, tiny improvements may mean the difference between seeing one’s country’s flag from the podium and watching from the stands.

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Winter Olympics Chat on The Takeaway

I had a lot of fun chatting with John Hockenberry for his radio show at The Takeaway.  We talked about several sports featured in the Sochi Winter Olympics.  The interview will be chopped into a few segments, beginning with curling and speed skating.  Click here for a preview.  If you are in one of the more than 220 cities where The Takeaway is syndicated, tune in for some physics fun!  I believe there will also be podcast episodes on iTunes.

It’s too bad I didn’t chat with John Hockenberry after yesterday’s skating.  Wow!  Russian skating is top notch, as proven in the team event.  Evgeni Plushenko is always a marvel to behold.  My younger daughter and I were rooting for Gracie Gold, and she delivered her personal best in a fantastic performance.  But, we could hardly keep still while 15-year-old Julia Lipnitskaia was on the ice.  Flexibility, grace, power, and full athletic prowess were on display as she nailed one jump after another and finished with a spectacular spin featuring three separate positions.  Angular momentum conservation was front and center throughout!

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Physics of a Dreadful Super Bowl

The Super Bowl was a real clunker.  If you are a fan of the Seattle Seahawks, you loved watching your team beat the Denver Broncos, 43-8.  If you are a Denver fan, you probably turned the game off at some point in the 3rd quarter.  For the rest of us who just wanted to see a competitive game, the Super Bowl was a real letdown.

Given that I wasn’t on the edge of my seat with the action, I had a chance to look at the game with my physics cap on.  Below are some physics thoughts I had while watching the game.

  • The game started at 49 F, which was much warmer than the predicted weather when I contributed to a piece on a cold-weather Super Bowl.  Cold weather effects were thus minimal and not a factor in the Broncos looking like Elway’s first three trips to the Super Bowl. 
  • 9:45 in the 1st quarter:  It was 2nd and 7 at the Denver 39.  Demaryius Thomas caught the ball at the Denver 40.  Kam Chandler at 232 lbs made a monster tackle.  Execution was perfect as Thomas was knocked back 5 yards after being hit just a bit above his center of mass.  Imagine hitting a one-ton car going nearly 3 mph.  That’s what the hit felt like for Thomas.  That 3 mph doesn’t sound like much until you realize you’re hitting a one-ton car!  In other words, you’re not going anywhere!
  • 5:49 in the 1st quarter:  Russell Wilson faced 3rd and 4 at the Seattle 39.  He fired a pass to Doug Baldwin at the Denver 49.  The 10-yard pass took just 0.4 seconds.  Wilson fired the ball with an average speed of 51 mph, which is what was needed for the 1st down.  Wilson threw much harder, more accurately, and had a better spiral than the future Hall-of-Famer Peyton Manning.
  • 4:24 in the 1st quarter:  at the Denver 43, Wilson faced a 3rd and 5.  He threw the ball from the Seattle 49 while Doug Baldwin was just crossing the Denver 38 (the 1st down line, by chance).  Baldwin caught the ball at the Denver 20, meaning Wilson timed the pass to hit Baldwin 18 yards down the field from where Baldwin was when the ball left Wilson’s hand.  The timing was perfect!  Baldwin made it to the Denver 6.
  • What I mentioned above is how Seattle dominated the 1st quarter.  Tackling was more fundamental, timing was better, and physics was utilized in ways that Denver could only dream of.
  • 12:05 in the 2nd quarter:  Seattle had 2nd and goal.  It was 8-0 at the time, when Marshawn Lynch got the ball at the 4.  He was hit at the 1-yd line, but the hit was off-center at his center of mass, which meant he merely bounced off the hit and into the end zone.  Again, poor tackling from Denver.
  • 11:24 in the 2nd quarter:  Denver was at their own 22.  Manning threw to his left to Demaryius Thomas.  The first hit was at the 24-yd line.  Byron Maxwell went below Thomas’s center of mass, followed by help from K.J. Wright and Bobby Wagner.  The first hit stopped Thomas’s linear momentum because the hit was just below the center of mass, thus creating just enough torque to arrest the motion.  Thomas was in trouble because as the help came, he had no forward momentum.  It was the perfect gang tackle.
  • Percy Harvin went 87 yards to open the 2nd half.  Harvin averaged 15.5 mph during his run.  He was speeding in a school zone!  His top speed was nearly 20 mph as he left Denver defenders in his dust.  Seattle won all phases of the game, most especially special teams.
  • 3:06 left in 3rd quarter:  Wilson hit Jermaine Kearse at the 17-yard line of Denver.  Three Denver defenders all hit Kearse at his center of mass, which meant Kearse just bounced off the tackles.  First, Danny Trevathan hit Kearse right in the center of mass, followed by Wesley Woodyard, and then Duke Ihenacho.  It was terrible tackling by Denver that led to Kearse scoring.  For some reason, Denver simply had poor fundamentals and poor physics in their tackling.
  • 2:39 in the 3rd quarter:  1st and 20 for Denver at the Denver 10:  Manning hit Wes Welker, and then Seattle’s K.J. Wright hit Welker just below Welker’s center of mass, ending Welker’s progress immediately.  It was a textbook tackle and a perfect example of Seattle utilizing the principles of physics much more than Denver.

Seattle obviously dominated Denver, but I sat there as a physicist and marveled at how well Seattle’s execution of play after play was consistent with what physics predicts for great football.  The physicist in me liked what he saw even if the game failed to live up to the hype!

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How will cold affect the Super Bowl?

There is much talk this year about the Super Bowl in a cold-weather city.  How will the cold affect play this Sunday at MetLife Stadium in East Rutherford, NJ?  Click here for a story I worked on with Kristian Dyer at Metro New York.

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Great Christmas Day Dunks from LeBron James!

The NBA does a great job putting games on Christmas Day that showcase the league’s biggest stars.  One of yesterday’s games had the Los Angeles Lakers hosting the two-time defending champs, the Miami Heat.  LeBron James had a few fantastic dunks during the game.  My favorite were two he got in the first half, both of which were assisted by Dwyane Wade.

With just under four minutes left in the first quarter, Wade drove into the middle of the key and threw the ball up after he was only a couple of feet into the lane.  James was flying in from the left and caught the ball when it was more than five feet from the basket.  The image below shows James just as he caught the ball from Wade (click on the image for a larger view).

James left the court at nearly 10 mph and took about half a second to leave the court, grab the ball, and slam it into to the basket.  He threw the ball into the hole at a speed of about 36 mph.  The ball was rotating at close to 145 rpm with respect to his right shoulder.  That rotational speed is about one third of the rotational speed of helicopter blades.

Moving on to under three minutes left in the first half, James had a dunk that was even more impressive that the one I showed above.  Wade drove down the right side of the key and after going about four feet passed the foul line, tossed the ball up with his right hand.  James was driving into the lane, just slightly left of center.  Wade’s toss actually went off the backboard before James caught it, and then followed with a dunk that had his head under the basket as the ball went through the hoop.  The image below shows James just as he is catching the ball from its flight off the backboard (click on the image for a larger view).

As with the first dunk I described, James left the court at nearly 10 mph and was airborne for about half a second before throwing the ball into the hoop.  The ball was moving about 13 mph away from the hoop when he caught it at the instant shown above.  James then reversed the ball’s trajectory by accelerating it to about seven times the magnitude of the acceleration due to gravity, or, simply, 7 g‘s.  He threw ball into the basket at a speed of nearly 23 mph.

Both dunks described here require an extraordinary amount of athleticism.  There may only be a tiny number of people walking the planet who could do what James did.  Those dunks were certainly Christmas treats for those of us watching!

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