Kind: captions
Language: en
This is Tom Brady. He's the greatest
American football quarterback of all
time. Holy sh Can you hear it go by you?
Yeah. Scary. He's won seven Super Bowls
and has thrown the most touchdown passes
in history.
Oh, that one hurt the chest. I heard
that right in the chest. I'm like glad
I'm not catching those. Every
quarterback takes pride in their ability
to throw a tight spiral. The tighter the
spiral you throw means the more control
you have of the football. We analyzed
his throw in detail. Have people shot
you in really slow motion for the
release and everything? Never. And
discovered something surprising. Even
Tom Brady can't throw a perfect spiral.
Just look said on his deep passes. No
matter how hard he tries to spin the
ball cleanly around its long axis, if
you look closely enough, you'll notice
this little wobble. Not only that,
there's a slight drift to the ball,
which means even Tom Brady can't throw
straight. Virtually all his long passes
curve to the right. But these aren't
mistakes. They're actually fundamental
to the physics of throwing a football
accurately. To find out why, we ran a
full computational fluid dynamics
analysis, tested spinning balls in a
wind tunnel, and even embedded sensors
in real footballs. That's crazy. Now,
admittedly, who are we to tell Tom Brady
anything about
football? I've never really played much
football. I grew up in Canada. I'd be
much happier to be playing hockey. Like,
why can't I throw at all? That is so
rough. Okay. Well, he'll walk you
through it. I'm not going to bother
doing it. Yeah. Yeah. Yeah. Yeah. Try to
do this. Overexaggerate the tilt. So,
instead of standing straight up, lean
forward. Lean like you're almost like a
short stop, right? Yeah. And like you're
falling over and then you're just here
like that. Good catch. So lean over a
little bit. I'm like not ready for it.
So get down like a short stop. Even
more. Even more. Yeah. Now throw it
sidearm. I feel like this is weird.
There you go. That was a better throw.
That is a better throw. It was really
good. What's the key to throwing like a
really tight spiral? The key to me is
first of all, you got to have very light
grip pressure on the football. I learned
over a period of time that I had to be
really efficient with my mechanics. I
had to have all my energy going right
toward the target with a very relaxed
posture. And then it's a really smooth,
efficient throwing motion. And then how
are you actually imparting the spin to
the ball? So you're really popping your
wrist at the end. So I can even go
really slow and just pop my wrist at the
end. And even that little bit of wrist
pop will create a little snap on the
ball as it releases from my fingertips.
Henry, you can't drop the easy one.
That snap and the spin it creates is the
key to Brady's record-breaking throw.
But the big question is why? I mean,
what does the spin actually do to the
football? It seems like such a simple
question, but the physics turned out to
be much more complicated than I
initially thought. In fact, physicists
studying the problem didn't get close to
the real answer until just 5 years ago.
So, let's break it down from the start.
A question for Tom is, can he throw the
ball without spinning it? Like a knuckle
ball? Yeah. Could you Can you knuckle
ball a football? Yeah, I could try. Can
I throw it underhand? Yeah, however you
want to toss it.
Even overhand, there's no way to do it
without getting a spin on it or it's
just going to mess with you. I mean,
you'd have to almost throw it sideways.
Yeah. Yeah.
Oh, that spun a little bit. When you
launch a ball without spin, perfectly
aligned with the direction of motion, it
seems like the air flowing over the ball
will be totally symmetric. But this is
unstable. Any slight disturbance, like a
tiny bit of wind, will cause more air to
hit one side than the other. And that
starts to change the ball's orientation.
And now more area on that side is
exposed to the oncoming air, so it
deflects even more. So drag on the ball
increases. It's pushed off course and it
can begin to tumble. The total drag
force on the ball is proportional to the
area presented to the airflow and the
drag coefficient. That's just a measure
of how streamlined an object is. Pointed
straight in the direction of motion. A
football is pretty streamlined with a
drag coefficient of just 0.14. That's
better than a bullet. But on its side,
the drag coefficient is 0.85. 85, which
is worse than a cow. Man, I'm learning a
lot today. That's what I'm going to use
with all the quarterbacks going, "Man,
your drag coefficient
sucks. What are we doing? We
need.14.85. No good." To make matters
worse, when a football is going
sideways, it exposes nearly 70% more
area to the oncoming air. And combined
with the higher drag coefficient, this
means that the drag force is 10 times
greater than when the football is
aligned with the throw. So an unspinning
ball can end up going sideways, meaning
it decelerates up to 10 times faster.
Plus, as it tumbles, the air pushes on
it in different directions, making it
move unpredictably. Now, in some cases,
you actually want this, like when
kicking the ball back to the other team.
Punters sometimes intentionally kick the
ball end over end so that it gets pushed
around erratically. That makes it far
harder for the opposing team to predict
where the ball's going to go and get
under it. But when you're passing to
your own team, you want the ball to be
predictable and go as fast and as far as
possible. And for that, you need
spin. The benefits of spin really became
clear in the mid 1800s during the Creian
War. Back then, soldiers were armed with
musketss that fired round lead balls.
And to make reloading faster on the
battlefield, these musket balls were
made significantly smaller than the
barrel. But when the gunpowder was
ignited, some of the expanding gases
would then escape around the bullet,
making the bullet's exit velocity
unpredictable. This, combined with
inconsistent manufacturing and the round
ball's poor aerodynamics, meant that
musketss were somewhat unreliable. There
was a British Army musketry instructor
who famously said, "I'm willing to stand
and be shot at all day long as long as
whoever's shooting at me with the smooth
musket promises to aim at me every
single time because he knew the bullet's
never actually going to go where the gun
is being aimed." All of that changed in
the fall of
1854. Russian troops huddled in
Sevastapole under siege by French and
British forces. The soldiers watched as
British troops set up on a distant
hillside. They were far out of standard
musket range, so the Russians weren't
worried. When
suddenly, a window shatters. They were
shooting through the windows of the
Russian barracks at their naval base in
Lost 900 yd away. They're shooting
bullets through the
windows. But these were no ordinary
bullets.
Eight years earlier, an enterprising
French army officer, Claude Etien
Minier, made a breakthrough. He
developed a conicle bullet with a hollow
base and an iron plug that would fit
into it. So when fired, the gas pressure
drove the plug into the base, which
expanded the bullet, pressing it firmly
against the barrel walls, so no gas
could escape. This made the bullet's
muzzle velocity much more predictable.
But it also enabled something else. The
expanded bullet could grip spiral
grooves carved into the inside of the
barrel called rifling. This imparted
spin to the bullet as it shot out. And
this is key because all spinning objects
have a fundamental quantity they
conserve, angular momentum. This helps
them resist changes in their
orientation. It's just like the spinning
top. Now, without spin, the top just
falls over like you'd expect. But if we
add a little bit of
spin, we can see that it resists changes
in its orientation. So if I give it a
little touch, it reorients itself in the
direction of its angular
momentum. A similar thing happens with a
spinning bullet. Its angular momentum
resists changes to its axis of rotation.
So even if wind applies an unbalanced
force to the bullet, it maintains its
orientation. This reduces drag and helps
the projectile fly further, faster, and
more accurately. The exact same thing is
going on when Tom Brady throws a tight
spiral. The important part of a spiral
is you feel the wind blowing at us. If
the ball wobbles at all, it's going to
catch a lot of resistance and the wind
and it's going to slow the velocity of
the ball down a lot and the accuracy.
The tighter the spiral and the more it
spins, the more it can just rotate
through the air and that the wind will
have a less effect on the ball. So for
any good quarterback, the ability to
throw a tight spiral is really important
when you play in windy conditions. A
spinning ball will maintain its
orientation and therefore cut through
the air with a smaller frontal area and
a lower drag coefficient. This all makes
sense, but here's where things get
weird. If the ball is maintaining its
orientation, then on a long hailmary
pass, it should stay pitched up like
this the whole time, just like when it
was thrown.
But that is not what happens. There's
kind of a paradox in football, which is
when you release the ball, you're
angled, say, positive 30°. Okay? And
when the receiver catches it, it's
angled negative 30°. Perfect. I love
that. So, what we just said was angular
momentum makes the ball hard to pivot.
Okay? But what we saw was it pitches
from this to this in 4 seconds. So, is
it turnover is what we would call that.
Now, turnover is essential to a good
throw because it means at every point
along the arc, the ball's orientation
stays closely aligned with its direction
of motion. That means it stays pointed
directly into the airflow, which
minimizes drag. Now, sure, you might
think this isn't that crazy. I mean,
arrows and birdies align themselves
along the path of the ark as well. But
that works in these cases because the
objects are front weighted. The feathers
catch the air and get pushed behind the
heavier tip, which leads the way.
But a football is totally different. I
mean, it doesn't have feathers or fins,
and its weight is evenly distributed
along its axis. So, it just can't use
the same mechanisms to align itself. So,
in 2020, the editor-inchief of the
American Journal of Physics decided to
figure it out. I was surprised at how
many bad explanations that were easy to
debunk got published. When you think
about it, it doesn't make any sense
because the air resistance would push
the nose of the football up and you want
the nose of the football to go down. So,
it's pretty curious. So, Price put
together a theoretical model to explain
the football's turnover. And today,
we're going to see whether his findings
hold up by simulating Tom Brady's own
throws in a wind tunnel. The idea of
having anything to do with Tom Brady,
whom I greatly respect, not only because
of his skill, but because of his work
ethic, it's
otherworldly. We have these sensors in
these balls, so we should be able to see
how fast balls are actually going from
inside the ball. And just to be sure,
I'm measuring the speed of these balls
the old-fashioned way. A decision I
might regret. Do you want to go right on
the side of the dummy with the gun? I'll
throw it right over your head.
I won't hit you. Trust me. Yeah. Right
there.
Perfect. You ready? Yep.
45. Maybe scoot just a smidge more that
way.
[Music]
Perfect.
Holy
46. You going to do another one? Yeah.
49. My god, that's scary. That's like 80
km an hour. But would you actually use
that speed in a game? That'd be a good
speed. That's a normal pass. That's like
terrifying.
And that's just for a regular throw. For
his long throws, the speed jumps even
higher. Over 60 mph. That's almost 100
kmh.
Now, I'm not about to step in front of
that cannon. I was not built for being
an athlete. You're built for analyzing
the That's right. I'm here for the data.
And that's why I've got Henry here. Oh,
that one hurt the chest. I heard that.
Sure. You don't want to swap in, Derek?
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And now back to Tom Brady.
Have people shot you in really slow
motion for the release and everything?
Did you ever watch that back? Never. You
guys ready?
I'm ready. Three, two, one.
Oh my god.
Are you good? You good, Ricky? Yeah.
Yeah, I'm good. I'm good. Is that plexi
or is that real glass? That's
plexiglass. That's incredible. You get
one shot of these things. Oh. All right.
I'd have given it my best. Should we try
one more? Even if the camera breaks. I
don't see the cracks. Wow. So, we can go
again. Let's try one more. Let me just
throw a little harder. Let's Let's go
again. I'm going to throw a little
harder.
[Music]
Now we're broken. That went right there.
Are we able to watch the throw back?
Good spiral.
Oh, that's so cool. The sensors show
Brady's maximum spin rate on this day
was 628 revolutions per
minute. So, armed with this data, let's
analyze Brady's throws in a wind tunnel.
How much data are you used to getting?
Zero. Really? When we when I played,
yeah, none of it was available.
So, this is the low-speed wind tunnel
here at the university. This wind tunnel
facility can get up to about Mach.2, so
20% of the speed of sound. Typically,
this wind tunnel is used in the
development of advanced wing geometries
for innovative sustainable aircraft
design. But today, it's being used for
football. We have just a Sting mount
mounted to a turntable. We actually have
a six component load cell here. And with
this six component load cell, we can
measure all three components of force
and torque. We then have an electric
motor, right, that we can spin to
basically simulate the spiral. First,
we're going to simulate one of Brady's
throws where the ball travels straight
into the airflow with his classic
spiral. And everything proceeds as we
expect. No significant forces or torques
develop. But during a game, a ball
doesn't travel like this in a straight
line. During any throw, its center of
mass follows a roughly parabolic
trajectory. So, let's say you align the
ball perfectly with this parabola when
you launch it. Well, then from the
ball's perspective, just a moment later,
this parabola starts to curve down away
from the ball, which means more air will
be hitting the underside of the ball
than on top. Now, you would expect this
would tilt the ball back, but that's
only what happens if the ball is not
spinning. If it is spinning, then the
situation is very different, which you
can see with this amazing demo. Imagine
this ring of golf balls is like a
cross-sectional slice of the football.
Here's what happens when I try and push
it back with this leaf
blower. I mean, it tilts back just like
you'd expect. But if I do the exact same
thing, but this time get the wheel
spinning, tilts out to the right. And
you can see why if we slow it down. So
as the ring passes the leaf bar, that's
where the force is applied. But each
ball still has momentum in the direction
of rotation. So it actually reaches its
peak 90° further along from where the
force is applied. And this is known as
gyroscopic procession.
So if the wind was hitting it, it's
going to keep the point up. So you'd
think that it would just push it back.
But because it's spinning, when you push
up, it actually tilts to the right. Oh,
interesting. But it doesn't stop there.
As the ball tilts right, it exposes more
area on that side. So now, because of
gyroscopic procession, the ball pitches
downward. And with more air hitting the
top of the ball, well, it's going to
deflect to the left. And that is going
to make the ball deflect back up. And
now we're back to where we started. So
this cycle is going to repeat. And since
this is happening continuously, the nose
traces out a circle around the direction
of air flow. So we get a slow wobble. We
used to joke whenever you would not
throw a tight spiral, you would call it
a tight wobbler. That was a Brett Favre
coin phrase. He let it go and have a
little wobble to it and he go, "Oh,
tight wobbler."
Now, if the ball were just traveling
straight, this would be the whole story.
But remember from before, the ball's
path is a parabola. Meaning that from
the ball's perspective, the oncoming air
is constantly dipping down away from it.
So the ball is trying to process around
the airflow direction, but that
direction is constantly
changing. For example, by the time the
ball has reached the bottom of the
procession, the airflow has moved down
too. And what that means is the ball is
not going to tilt out to the left as
much as you'd expect. So when it
processes back up, it doesn't go as high
as where it started. And over time, it
is this that gradually pitches the nose
of the football down, keeping it aligned
with its parabolic
path. I can visualize it all. Your fancy
science words. I I'm going all the way
back to my high school days. I was a
very average science student. So, but
you're you're teaching me a lot. As the
ball goes through the air, there's going
to be more air resistance on the bottom
of the ball than on the top. The front
of the ball, not the back, because
that's hitting the wind first. The front
bottom of the ball. Okay? And so what
that means is it creates this processive
effect that pushes it out, push it down,
push it right. It creates a wobble no
matter what you do. So wobble is
actually not only impossible to avoid,
but it's essential to make sure that the
ball follows the path that you want it
to follow. You can see this in the wind
tunnel. We've tilted the ball up by 3°
and it's free to pivot in any direction.
Yeah, you're definitely seeing a pitch.
Oh, that's awesome. What we're seeing is
it's starting out aligning itself about
3° off, you know, cuz that's how we spin
it up. But as the air flow starts, it's
pointing itself in the direction that
minimizes drag. That's so cool. I mean,
that's exactly what we were expecting.
But it's still incredible to see it in
person. If you look at a real football
in flight, you'll notice that it spends
more time angled slightly to the right
when thrown by a right-hander. That is
what creates the force which through
procession gradually pitches the nose
downward. It creates the turnover effect
that Tom Brady was talking about. Just
want to reframe the wobble is not
necessarily a bad thing. Okay, good.
Manny had a good wobble on the balls,
but he found a way to complete a lot of
touchdowns that way. But the rightward
lean of the ball also has an unintended
side effect.
Something we've heard is that for
right-handed throwers, the ball will
drift right and for left-handed
throwers, the ball will drift left. Do
you think that's true or is is that
something you notice? So, I wouldn't
necessarily agree with that. So, we got
Tom to throw straight down one of the
lines on the field. Is a drone set?
That's a pretty straight throw. Henry,
don't move. You're making it look bad.
I'll stay I'll stay planted. The more
still you you go, the better it looks
for my throw. It's like a catcher when
you frame the pitch. I'll frame it. I'll
frame it. From ground level, his passes
looked amazingly straight. But from the
drone, if you watch closely, just at the
end of the pass, the ball does drift off
to the right. This is because up until
now, we've been ignoring a very
important aerodynamic effect, which is
lift. When the ball is tilted to the
right, it generates lift out in that
direction. The more it's tilted, the
larger this force is, the rightward tilt
is required to get the ball to turn over
during its parabolic path, but it does
mean that right-handed throws tend to
drift right. The effect is subtle, but
some players notice it intuitively. In
the fall of 1991, Jerry Rice, generally
considered the greatest wide receiver of
all time, changed quarterbacks. In place
of the right-handed Joe Montana, he was
now catching passes from the left-handed
Steve Young. And for Rice, something
felt off. He wasn't sure exactly why,
but he said the throws were coming up
short. Of course, what was actually
happening was that the ball was drifting
away from where he expected it to be.
Joe Montana's right-handed throws
drifted to the right, whereas Steve
Young's drifted left. It's a subtle
effect, but it's all part of the
procession that minimizes drag on the
ball and lets it fly farther, faster,
and more
accurately. So, it's not because you're
a bad quarterback throwing it with a
wobble. It's because wind, you know.
Okay. So, what if you're in a dome and
there's no wind? See, that's a great
question. So, I'm just saying this is
just air resistance. So, even in even in
a dome, the same thing would happen.
Whether in an outdoor stadium or a
closed top dome, the ball will always
wobble. But outdoor stadiums are
significantly harder to throw in because
of the wind. With the ball being thrown
at 50 to 60 mph, most of the air flow
over the ball is due to its own motion.
But in winds gusting over 15 mph, the
weather starts to play a major role. We
commissioned the NFL data team to do an
analysis of completion percentage in
outdoor stadiums versus indoor domes.
And they found that throws in indoor
stadiums are consistently more accurate
no matter the distance. So maybe Brady
was hardone by Foxboro, New England's
stadium. Do you prefer to throw in a
game when it's no wind? Do you prefer
wind, rain, snow? Does it matter?
I preferred
outdoor, 70°, humid, tiny little breeze
just to keep you cool. Right. But why
did you like being outdoors as opposed
to being in a dome? I felt like my depth
perception was a little better outside.
Um, I like just the natural feel of the
natural air. The dome always felt um
like a vacuum. Do you think you had an
edge if the weather was bad compared to
other quarterbacks?
Um, I would say yes. And the reason why
is I'd say I practiced in it all the
time. And I think um getting used to the
conditions and the familiarity of the
wind, of the humidity, of the rain, of
the snow, you know, grass field, turf
field. I knew exactly what to wear for
every single condition. I played 23
seasons, 100 to 120 practices a year. So
that's over two 2,000 plus practices.
That's crazy. You know the thickness you
want in your sleeves. You go, "Okay,
what's temperature?" It's 50°. Okay,
this is the shirt I wear when it's 50°.
Oh, it's 35°. This is the two shirts I
wear when it's 35°. You know, this is
the muff that I wear. You know, this is
how many heat packs I put in the muff to
keep my hand warm when it's 30° versus
50°. You had it all dialed in. You just
have to I mean, you just observe over
time and you, you know, get better and
better. It's a lot like an F1 car, you
know? Everything is just fractions of,
you know, things to do to make yourself
feel the most comfortable.
So maybe Brady is a bit more scientific
than he gives himself credit for. Over
383 career games, more than 7,700
completed passes, and tens of thousands
of hours on the field, Brady intuitively
understands all the physics we've just
analyzed. Plus, he knows how to harness
these effects to get the ball where he
wants it to go with just a few seconds
to throw it. In a game where perfection
is impossible, he's internalized all the
complex physics, the kinematics, the
aerodynamics, and he still makes it look
simple.
Yeah, I don't have to move.
So, we actually made a video together
with Tom Brady teaching us how to throw
a football. And if you want to learn
more about that, you can check it out
right here.
Now, what we got for you are some balls
that you've never thrown before. Oh god,
what do you guys got cooked up? But
we're not done yet. What the heck?
In other sports, surfaces are engineered
down to the smallest detail to control
air flow. But footballs, they've hardly
changed in decades. So, we tested
whether a football's design is really
optimal. And to find out, we had Tom
Brady throw a series of custom balls,
including one built to eliminate his
spin entirely. I didn't even know how
you could throw that. Now, in
investigating this, we actually
uncovered a secret technique that teams
are using to modify their balls and give
their players an advantage. But, we'll
get to that in a future video. So, make
sure to subscribe and stay notified and
we'll see you then. That's insane.