18 January 2018

Playing with Science Mix

StarTalk's Playing with Science put together a nice mix from the first two seasons.  I get to chime in on the show.  Click the link below for last night's episode.
It was a lot of fun working with Playing with Science in 2017!  Who knows what's in store for this year with the Winter Olympics and World Cup ...?

31 December 2017

Physics and Psychology Aid Callahan's Punt Return TD!

The Chicago Bears finished a rather dreadful season with a loss to the Minnesota Vikings today, 23-10.  The Bears did have a fun play that I got to analyze for TuneIn's Ho Huddle.  With just over six minutes left in the first half, the Vikings faced a 4th and 9 at their own 16-yard line.  Vikings' punter Ryan Quigley (#4) punted the ball from Minnesota's 7-yard line (click on image below for a larger view).
You can see in the above screen capture that Quigley was right on the 7-yard line when the ball left his right shoe.  The ball was punted at almost 60 mph and over 60 degrees to the horizontal.  For an incredibly short amount of time, the force between shoe and ball on a good punt can be over 1000 pounds.  The punted ball traveled 53 yards and had a hang time of 4.24 seconds.

The problem for the Vikings was that the Bears' Tarik Cohen (#29) played the perfect decoy.  He was on the right side of the field and acted as if he was going to catch Quigley's punt.  But Bryce Callahan (#37) was on the left side of the field and caught the punt while sliding on his own 40-yard line (click on image below for a larger view).
Look at Cohen with his arms out like he's about to catch the punt!  The Vikings' Jayron Kearse (#27) is running full speed at Cohen while Callahan has just caught the punt.  The screen capture below shows when Callahan got up after his slide (click on image for a larger view).
You can see the purple blurs heading toward Cohen!  I couldn't tell from the video I watched, but Quigley should have been yelling at his teammates, telling them where his punt was headed.  Even though the Vikings were at home, the noise level could have been in the 70 dB - 100 dB range, which corresponds to the sound a vacuum cleaner makes all the way up to what a busy subway sounds like.  Quigley's teammates down the field probably wouldn't have heard him if he was yelling.

Callahan could get up after his slide and run because the NFL doesn't use college football rules.  The screen capture below shows that Callahan had many blockers in front of him (click on image for a larger view).
The Vikings are headed to the right while Callahan is preparing to run down the left side of the field.  Cohen did such a good job selling the fake that Kearse nearly ran into Cohen and had to veer off to Cohen's left upon realizing that Cohen didn't have the ball.  Check out the screen capture below, which shows five Vikings near Cohen, all realizing too late that they ran after the wrong player (click on image for a larger view).
Meanwhile, Callahan was hitting a top speed of 19 mph in Vikings' territory (click on image below for a larger view).
Callahan crossed the goal line at about 16 mph, having slowed a little to celebrate (click on image below for a larger view).
A lot of great physics for sure, but psychology had the Vikings off course and chasing the wrong Bear!  The Bears finished 5-11 this year, but left me with a fun play to analyze before bringing their season to a close.

Chuck Nice of Playing with Science joined me on today's segment.  As he always does, Chuck set up the play really well before tossing it over to me for the nerdy stuff.  Click here for our segment.  The NFL regular season finished up today, but like the 13-3 Vikings, we football fans are anxious for the playoffs to begin!

28 December 2017

Extended Classic: The Science of "The Catch"

This past Wednesday night's episode of Playing with Science took another look at Odell Beckham Jr's famous one-handed catch.  Click on the link below to hear me discussing the physics behind the catch.

It's a great time of year to talk football physics!

24 December 2017

Gurley Outruns Titans!

The Los Angeles Rams edged the Tennessee Titans today, 27-23.  The Rams were helped in their efforts by an incredible run by Todd Gurley (#30) that took place with less than five minutes to go in the first half.  The Rams faced 2nd and 11 from their own 20-yard line.  Quarterback Jared Goff (#16) -- no relation! --was in the shotgun (click on image for a larger view).
You can see Gurley standing to the right of Goff.  I've also circled Johnathan Cyprien (#37), the strong safety for the Titans.  Cyprien was blitzing.  The screen capture below shows Cyprien's view of Goff before the play started (click on image for a larger view).
After Goff took the snap, he backpedaled to the Rams' 10-yard line before throwing a screen pass toward Gurley.  But Gurley was lucky to even receive the ball because Cyprien almost tipped Goff's pass.  Check out the screen capture below (click on image for a larger view).
I've cropped the original screen capture and blown up the image, which is why it's a little grainy.  Using a standard length measurement associated with Goff's height, I estimated that Cyprien's fingers missed the football by less than four inches.  Football really is a game of inches!

Gurley caught Goff's screen pass at the Rams' 15-yard line, which was 5 yards behind the line of scrimmage (click on image for a larger view).
Notice that Gurley is turning clockwise (as seen from above) in preparation for his run.  What got Gurley to the end zone 10.5 seconds later wasn't just the blockers in front of him.  The Rams benefited from Gurley's amazing speed.  Gurley simply outran all the Titans!  Not long after crossing midfield, Gurley hit a maximum speed of almost 22 mph (click on image for a larger view).
Look at those Tennessee defenders trying to catch Gurley!  To put his 22-mph speed into perspective, consider Usain Bolt.  At the peak of his sprinting powers, Bolt exceeded 27 mph.  But he wasn't wearing pads and a helmet that total almost 20 pounds!

Check out Gurley scoring below (click on image for a larger view).
Fast-twitching muscles and blinding speed on the part of Todd Gurley allowed Jared Goff to throw a football 5 yards and get credited for an 80-yard touchdown pass.  How great is that?

I tracked where Gurley was as he passed each yard line.  I then determined his velocity component in the direction perpendicular to the yard lines.  The plot below shows Gurley's run just after he caught the ball and got going (click on image for a larger view).
Gurley ran most of those 85 yards along the left hash marks.  Just before reaching the Titans' 15-yard line, he ran toward his right to avoid tacklers.  His speed dropped as he neared the goal line, but not quite as much as the above graph indicates.  By running toward his right, Gurley added to his velocity a component parallel to the yard lines.

Chuck Nice of Playing with Science joined me on TuneIn's No Huddle to chat about Gurley's magnificent run.  Click here for our segment.

20 December 2017

Extended Classic: The Immaculate Reception

Tonight's episode of Playing with Science revisits the Immaculate Reception, which was a famous catch (or not?!?) by Franco Harris of the Pittsburgh Steelers during the 1972 NFL playoffs.  Click on the link below to hear me and others talking football physics.
 It's always fun talking sports physics, especially physics on the gridiron!

17 December 2017

A Bullet from Keenum to Diggs!

The Minnesota Vikings obliterated the hapless Cincinnati Bengals today, 34-7.  With less than seven minutes to go in the second quarter, Case Keenum (#7) fired a bullet to Stefon Diggs (#14) that pushed the Vikings lead to 23-0, but Diggs took a couple mighty hits after scoring.  Check out the Vikings' shotgun formation on 2nd and 16 from the Bengals' 20-yard line (click on image for a larger view).
Note Cincinnati cornerback Tony McRae (#29) covering Diggs.  Another look at the formation shows the one Bengal on defense that you can't see in the above screen capture.  Check out the view from behind Keenum (click on image for a larger view).
Standing just inside the Bengals' 5-yard line is free safety Clayton Fejedelem (#42).  McRae and Fejedelem were about to become the bread in a Stefon Diggs sandwich!

Keenum took 2.24 s from the snap to throw his pass.  The Bengals rushed four, but the Vikings had five offensive lineman in pass protection.  Keenum threw the ball from the Bengals' 27-yard line while inside a perfect pocket (click on image for a larger view).
That's some great blocking for Keenum!  Diggs was running a post route and Keenum fired the ball at 50.1 mph at 15.8 degrees above the horizontal.  The ball reached Diggs 1.30 s later at 46.4 mph.  Air drag was about 17% of the ball's weight just after Keenum released the ball.  The plot below shows the trajectory of Keenum's pass (click on image for a larger view).
Diggs was running about 16 mph when he caught the ball at the goal line (click on image for a larger view).
But notice what was about to happen to Diggs.  Immediately after crossing the goal line, Diggs was met on his left by Fejedelem and on his right by McRae.  The two Bengals crunched Diggs a couple yards into the end zone.  Fejedelem hit Diggs with an average force in excess of 500 pounds, and that was very quickly followed by a hit from McRae with a similar force.  Look at the start of the hits (click on image for a larger view).
From another view, you can see what that 500-pound hit by Fejedelem looked like (click on image for a larger view).
Now look at the next screen capture as McRae gets his hit on Diggs (click on image for a larger view).
What's incredibly lucky for Diggs is that he was ever-so-slightly ahead of the two Bengals' defenders.  The last image I'll show you of the hits demonstrates that fact, but still makes it clear that football collisions are violent (click on image for a larger view).
Diggs surely thought a little pain was worth the score!  Had he not been a tiny bit ahead of his tacklers, he might have felt forces greater than 1000 pounds during a very short time interval.  Don't forget Newton's third law though, though.  The two players who tackled Diggs felt equal-magnitude forces from Diggs.

After Diggs got up from the two big hits he took, he celebrated by going to the back of the end zone and fired the ball into the purple padding behind the end zone.  He actually threw the ball at about 41 mph, which wasn't that much slower than the pass he had just caught from Keenum!  Check out Diggs throwing the ball (click on image for a larger view).
Gary O'Reilly of Playing with Science joined me on TuneIn's No Huddle to discuss the play.  As always, Gary did a great job setting the play up before I threw some physics into the discussion.  Gary noted that if Diggs doesn't spike the ball when he scores, watch out for his throw!  Click here for our segment.

10 December 2017

Snow Physics Helps the Bills!

Who doesn't love playing football in the snow?  If you get lucky and have some snow on Thanksgiving, you go all out in the Turkey Bowl, diving for catches and sliding in the snow.  How great is it that professional football keeps being played whether it's raining, windy, or snowing?  The Indianapolis Colts visited the Buffalo Bills today and were treated to wind and snow.  The Bills won in overtime, 13-7, in a game in which snow physics played a major role.

Scoreless near the end of the first half, the Bills had 1st and goal at the Colts 8 yard line.  Check out the formation below (click on image for a larger view).
I've circled four key players in the above screen capture.  Look at that field and note that the image isn't crisp because it was snowing at the time.  Players in snow can lose about 30% of the friction on their shoes from what they're used to.  They can't run with long strides or they risk slipping.  A football brought from a warm locker room can lose a couple psi because air molecules aren't bouncing around inside the ball as much as they were in the locker room.  The air temperature in Buffalo at the time of the above play was about 30 F.  Air at that temperature is about 9% denser than air in a balmy 75-F stadium, and that added air density makes for more air resistance on passes.

Snow physics helped the Bills score from the formation shown above.  The Colts rushed just four, but there is a reason I circled left defensive end, Margus Hunt (#92) in the above image.  Check out the image below, which is 2.6 s after the above image (click on image for a larger view).
Margus Hunt slipped and fell forward in the snow!  All of a sudden, the right side of the Bills line had no rush to block and there was no defender on that side to swat the pass.  By the time Hunt got up, it was too late.  The screen capture below shows Bills quarterback Nathan Peterman (#2) releasing his pass at 45 mph and 21 degrees above the horizontal (click on image for a larger view).
The ball was released outside the Colts 10 yard line.  Bills wide receiver Kelvin Benjamin (#13) only reached 11 mph prior to crossing the goal line.  He caught the pass 1.43 s after Peterman released the ball (click on image for a larger view).
Note Colts cornerback Christopher Milton (#28) looking over his left shoulder.  He had gotten turned around in the snow and didn't have enough shoe friction in the snow to close the gap and stop Benjamin from making the catch.  Benjamin caught the pass while it was moving at about 41 mph.  Benjamin's padded gloves increased friction with the ball so that he could secure the catch in the snow.  Check out his perfect two-handed catch below (click on image for a larger view).
Milton certainly had a great view of Benjamin's catch!  Credit Benjamin for superb fundamentals.  Though Benjamin couldn't reach his top speed while running with short strides in the snow, slippery snow physics hurt the Colts' defense!

The trajectory of Peterman's pass is shown below (click on image for a larger view).

The ball only got about 5 yards above the snow on its flight to Benjamin's gloves.  But that was all the height needed for a pass thrown at the 11 yard line and caught halfway into the end zone near the right sideline.

Chuck Nice of Playing with Science joined me on TuneIn's No Huddle to discuss some snow physics and the above play.  Chuck was great setting up the play and then I rambled about the physics.  Click here for our segment.  We got a little snow in Lynchburg yesterday, but I'm jealous of all the snow in Buffalo!

03 December 2017

Tarik Cohen's INSANE Punt Return

The Chicago Bears lost a nail-biter to the Francisco 49ers today, 15-14.  But the Bears didn't disappoint as football fans were treated to an incredible punt return in the second quarter.  San Francisco's Bradley Pinion (#5) received the snap and launched his punt at about the 49ers 7-yard line (click on the image for a larger view).
Pinion's punt traveled about 54 yards in the air with a hang time of 4.2 s.  That's a typical hang time and should have given the 49ers plenty of time to get downfield to defend against the punt return.  But their defense looked more like a Tour de France peloton than proper football pursuit!

Chicago's Tarik Cohen (#29) fielded the ball at the Bears 39-yard line (click on the image for a larger view).

Note that Cohen caught the punt just to the left of the painted 40 on the field.  Chaos ensued after Cohen's catch!  He first noticed two 49ers about 8 yards in front of him.  He then ran backwards and to his right.  Check out the screen capture below, which is 2 s after Cohen caught the punt (click on image for a larger view).
San Francisco's Aldrick Robinson (#19) had both his hands on Cohen!  But Cohen kept running backwards.  Check out the 49ers pursuit when Cohen got to the other side of the field (click on image for a larger view).
There are SEVEN 49ers running after Cohen with no blockers in their way!  The problem is that they all ran as one.  Instead of fanning out and covering more of the field, they looked like a cycling peloton or a flock of birds changing directions.

Cohen ran back across the field to nearly the spot where he caught the punt.  His teardrop-shaped path backwards towards the other side of the field took 8 s off the clock!  He then hit his own 40-yard line and turned on the jets.  He sprinted 50 yards, hitting a top speed of just over 20 mph.  Slowing to 15 mph for the final 10 yards, Cohen crossed the goal line nearly 15 s after he caught the punt! (click on image for a larger view)
Though he was credited with a 61-yard punt return, Cohen ran about 119 yards in total!  That was nearly TWICE was he was credited for!  He also had to catch the punt while staring into the sun.  That was one amazing punt return!

Gary O'Reilly of Playing with Science joined me on TuneIn's No Huddle to discuss this play.  Gary did a great job setting up the play and then I yapped some physics.  Click here for our segment.  A fun play to analyze!

26 November 2017

Wildcat Keeps Sanu Perfect!

The Atlanta Falcons beat the Tampa Bay Buccaneers today, 34-20.  The play I analyzed for TuneIn's No Huddle took place early in the 2rd quarter and broke a 3-3 tie.  The Falcons faced a 3rd and 1 from their own 49.5-yard line.  Former Rutgers quarterback and Falcons wide receiver Mohamed Sanu (#12) was in the shotgun.  The Falcons had pulled the wildcat formation out of their playbook.  Running back Tevin Coleman (#26) was lined up to Sanu's left.  Julio Jones (#11) was in the left slot with the Bucs' Robert McClain (#36) lined up opposite Jones.  The screen capture below shows the formation and defensive set (click on image for a larger view).
Did the Bucs think Sanu would run for the 1st down?  If so, that was a costly mistake!

McLain looked like he got a little lost on the play.  He left Jones not long after the snap.  He turned to cover the wide out.  That left Jones in single coverage with Bucs safety Justin Evans (#21).  Not long after the snap, Sanu faked the hand-off to Coleman, but the ball was bobbled.  Check out the screen capture below as Coleman's right hip knocked the ball out of Sanu's hands (click on image for a larger view).
Sanu recovered the ball from the air and threw it 3.10 s after the snap.

By the time Sanu threw the ball, Jones was running at about the Bucs 33-yard line.  Though Jones averaged almost 16 mph during the entire snap-to-score play, he averaged 19 mph after the ball was thrown.  Sanu released the ball at 53.2 mph and 43.8 degrees above the horizontal.  The ball took 3.27 s to reach Jones.  Air resistance was about 19% of the ball's weight, which is why the ball landed in Jones' gut at 47.1 mph.  Check out the ball's arrival in Jones' gut below (click on image for a larger view).
Jones was falling when he caught the ball, but physics helped him score as his linear momentum took him into the end zone!  See the score below (click on image for a larger view).
Julio Jones may have hated watching yesterday's Iron Bowl, but he surely loved watching that football fly at him from the wildcat position!  And how about Mohamed Sanu?  He is now 6 for 6 in his NFL career with 3 TD passes.  That makes for a PERFECT 158.3 passer rating!  Check out the trajectory of his latest TD pass below (click on image for a larger view).
Sanu's pass soared 16 yards above the turf before reaching Jones.  It was an amazing play for sure.

Chuck Nice from Playing with Science joined me on today's Check Down segment.  He did an amazing job setting up the play before I yapped about the physics.  He loved it when I noted that Sanu's spiral was about 10 revolutions per second or 600 rpm, which is one-and-a-third times faster than a helicopter's rotor blades!  Click here for the live bit we did for TuneIn.

22 November 2017

Extended Classic: Hail Mary!

Not long ago, while I was at Kenyon College for an invited talk, I recorded three extended segments for episodes of Playing with Science.  Tonight's episode may be reached via the link below.

It was a lot of fun talking more gridiron action.  Just in time for Thanksgiving!

20 November 2017

From Saints Sandwich to Touchdown!

No Huddle asked me to analyze a nice touchdown thrown by Washington Redskins' quarterback Kirk Cousins to Ryan Grant.  Unfortunately for the Redskins, the New Orleans Saints had a monster 4th-quarter comeback and won the game in overtime.

The play I analyzed took place late in the 3rd quarter with the shot clock winding down.  The Redskins faced a 3rd and 7 from the Saints 40-yard line.  Cousins (#8) was in the shotgun and just prior to the snap, the Saints sent both safeties in for a blitz into the middle of the Redskins' line.  Washington had seven blockers, including running back Samaje Perine (#32).  But the Saints had eight rushing the quarterback and it doesn't take a rocket scientist to know that 8 is greater than 7.  Kirk Cousins was about to get smashed!

The Saints' safeties had a running start on the blitz.  Cousins received the ball 0.43 s after it was snapped and the hungry Saints defenders were rushing for the sack.  Ryan Grant (#14) was on the right side of the Washington formation.  Check out the start of the play below from the screen capture I took (click on image for a larger view).
Grant sprinted to the right sideline as Cousins held the ball long enough for Grant to get open.  The left side of the Redskins' line broke down and Cousins was going to be blindsided by defensive end Alex Okafor (#57).  Cousins had taken four big steps back and threw the ball a full 2 s after he received the snap.  Just as he threw, he became the meat in a Saints sandwich as he got crushed by Okafor and safety Vonn Bell (#48).  Safety Rafael Bush (#25) piled on after the initial hit for added damage.  Check out the carnage below (click on image for a larger view).
Not much fun for Cousins, was it?  But he got the ball where it needed to be!  Cousins released a great spiral into low-Earth orbit at the speed of 46 mph at 30.7 degrees above the horizontal.  The ball traveled just over 38 yards in total horizontal distance, reaching a maximum height of about 8 yards above the turf, and took 2.1 s to reach Grant.  It landed in his hands at about 41.6 mph.  An air resistance force of about 15% of the ball's weight was acting on the ball while in flight.  Check out the graph below of the ball's trajectory (click on image for a larger view).
Grant had run past two unsuspecting Saints defenders and was wide open for the catch.  Check out just how open he was (click on image for a larger view).
Where was the defense?!?  All that was left for Grant was a stroll into the end zone with perhaps a little taunting thrown in.  After scoring, he tossed the ball into yet another low-Earth orbit.

For the audio on TuneIn Radio, click here.  Gary O'Reilly of Playing with Science joined me on the show and did a wonderful job setting up the play.  During my analysis of the play, I was interviewed by Alissa Smith of the Lynchburg News & Advance.  Gary O'Reilly was kind enough to give Alissa a few comments for her story.  Click here for the story that appeared in the Monday, 20 November 2017 edition of the paper.

12 November 2017

A Great Fake Punt!

For this week's appearance on TuneIn Radio, I got to discuss a great fake punt in the Jacksonville Jaguars' overtime win against the Los Angeles Chargers.  At the end of the first quarter with no score, the Jaguars were lined up for a punt.  It was 4th and 7 on their own 44-yard line.  Brad Nortman was set to receive the snap from long snapper Matt OvertonCorey Grant was behind the Jaguars' line to the right of Overton.  Check out the screen capture I got of the formation below (click on the image for a larger view).
I circled Nortman, Grant, and Paul Posluszny, who followed my yellow arrow into an incredible block.  Nobody was lined up across from Overton, and thus a lineman didn't notice that Overton was ever-so-slightly angled toward Nortman's right.  He would direct snap the ball to Grant.  Check out the hole that the Jaguars' line opened up for Grant, and note Posluszny's great block to seal the side of the hole to Grant's right (click on the image for a larger view).
Notice Grant is headed toward the massive hole as Posluszny runs right in front of him.  Grant had faked to his right to give Posluszny time to get in the hole for the seal block.  Nortman rolled out to his left to help sell the fake.

The Chargers had two shots at stopping Grant.  The first was by #40, Chris McCain.  Grant stiff-armed McCain at the Jacksonville 45-yard line as McCain dove toward Grant.  The problem with McCain's tackle attempt is that McCain's force mostly pulled downward on Grant's legs.  That wasn't going to alter Grant's forward linear momentum!  Check out the screen capture below (click on the image for a larger view).
McCain tried for Grant's feet, but Grant stabilized himself just a like a tightrope walker does.  Notice both his arms are extended outward.  That makes it harder to move Grant's center of mass outside his shoes, which would cause a gravitational torque to make him fall.

The second and last hope for the Chargers was #20, Desmond King.  He had an open-field shot at Grant near the Los Angeles 42-yard line.  But once Grant spied King, Grant shot to his left.  When King drove for Grant, Grant hurdled over nine feet horizontally to avoid having his legs taken out.  Look at Grant's athleticism below (click image for a larger view).
King dove, but Grant leapt to daylight.  Once Grant cut hard to his right at the Los Angeles 35-yard line, he outran the defense to the goal line.  Those hard cuts can lead to well over 100 pounds of force on a running back's legs.  It's no wonder the average career length for an NFL running back is only about four years!

What I especially loved about the play is that it took nearly 11 seconds to complete.  Someone could have jogged 10.6 mph along the sideline at the snap of the ball and gone 56 yards to the goal line in the time it took Grant to score.  Grant was through the initial hole at 15 mph, and then hit a maximum speed of about 19 mph halfway into Los Angeles territory before scoring at nearly 18 mph.  A sideline jogger that went 56 yards would have watched Grant run a total of about 85 yards!

Chuck Nice of Playing with Science joined me on today's radio segment.  Chuck did a great job setting up the play and then I yapped some physics.  Click here for our segment on TuneIn's No Huddle.  It was a lot of fun talking football physics!

11 November 2017

Return from Kenyon College

I returned from my visit to Kenyon College today.  Friends and colleagues know why the trip was difficult for me.  Kenyon College has been a special place for me since 1999.  Unfortunately it now represents a place of broken promises and betrayal.  What helped me considerably was the warm reception I received upon meeting up with former colleagues.  It was great chatting with old friends again.  I also enjoyed meeting new people and spending a few minutes discussing my research with Kenyon's bright physics majors.  I had fun giving my talk.  The photo below shows me a couple minutes before my talk began (click on the image for a larger view).  Pizza helped attract a few extra students!
The chalkboard shows some belated Halloween math I used to entertain people before I got introduced.  Nothing like a little mathematical nonsense to lighten an audience!

07 November 2017

Talk at Kenyon College this Friday

I will return this Friday to where my post-doctoral career began, Kenyon College in Gambier, Ohio.  There are many reasons why I look forward to being back at Kenyon, but there are several personal reasons why the trip will be difficult for me.  I'll do my best to put those reasons aside and have a great trip to a place that still means a lot to me.  I certainly look forward to discussing three of my research areas with the good people at Kenyon.  Either click here or on the poster below for information about my Friday talk.