The physics of a football pass

Reverend Conehead · Nov 8, 2019

I don't know that much about physics, but there's one thing I've wondered about. When a QB throws a long pass, the front nose of the ball starts off pointed up and then the ball moves in an arch with the nose slowly moving down. By the time the WR catches the ball, the front nose is pointing down. Why does this change happen? When he throws it up, why doesn't the front nose of the ball continue to be pointing up for the entire pass?

EST_1986 · Nov 8, 2019

Gravity?

Flamma · Nov 9, 2019

EST_1986 said:
Gravity?

Yes. Or the ball is heavier than air, your choice.

Reverend Conehead said:
I don't know that much about physics, but there's one thing I've wondered about. When a QB throws a long pass, the front nose of the ball starts off pointed up and then the ball moves in an arch with the nose slowly moving down. By the time the WR catches the ball, the front nose is pointing down. Why does this change happen? When he throws it up, why doesn't the front nose of the ball continue to be pointing up for the entire pass?

Dude! I must have played over 1000 football games in my life and never once thought of that. I drank over 10,000 beers in my life, many of them after football games and never once thought of that. And I played WR!!! Now if I were to throw a pass the tip of the ball might very well remain pointing skyward. But that's me.

I don't know how to answer this. It's not weight related. My best guess is since the ball is on an arc the tip reaches the top first and therefore starts to fall first followed by the rest of it. That's absolute crap, but my best guess.

EST_1986 · Nov 9, 2019

Flamma said:
Yes. Or the ball is heavier than air, your choice.

Dude! I must have played over 1000 football games in my life and never once thought of that. I drank over 10,000 beers in my life, many of them after football games and never once thought of that. And I played WR!!! Now if I were to throw a pass the tip of the ball might very well remain pointing skyward. But that's me.

I don't know how to answer this. It's not weight related. My best guess is since the ball is on an arc the tip reaches the top first and therefore starts to fall first followed by the rest of it. That's absolute crap, but my best guess.

OP smoking week not drinking beers that’s why this is on his mind lol

Reverend Conehead · Nov 9, 2019

EST_1986 said:
Gravity?

Yes, of course it's gravity, but why doesn't gravity pull it down exactly how it went up, with the front nose pointing up? Somehow I got through school without taking a physics course. I'm just curious. Maybe this is a topic for Physics Girl on Youtube.

Flamma · Nov 9, 2019

Reverend Conehead said:
Yes, of course it's gravity, but why doesn't gravity pull it down exactly how it went up, with the front nose pointing up? Somehow I got through school without taking a physics course. I'm just curious. Maybe this is a topic for Physics Girl on Youtube.

Gravity has nothing to do with it, you're heavier than air you're going to fall. Just like a helium balloon rises because it's lighter than air. Keep gravity out of this.

Reverend Conehead · Nov 9, 2019

Flamma said:
Gravity has nothing to do with it, you're heavier than air you're going to fall. Just like a helium balloon rises because it's lighter than air. Keep gravity out of this.

But ... but ... my teacher said that gravity pulls stuff down.

joseephuss · Nov 9, 2019

It is the spin. If you could somehow hurl the ball downfield without spin, it would then tumble in the air. Rockets and missiles use wings to balance out their flights. Football, like bullets utilize spin to provide a somewhat smooth flight.

joseephuss · Nov 9, 2019

I'll forgot to mention that punts sometimes start with the nose of the ball leading the way, but if not hit true the tail leads the way down. You usually hear it referred to as the punter not getting the ball to turn over. The punt didn't have sufficient spin for it's trajectory, so instead of it coming down nose first it tumbles and the tail takes the lead.

408Cowboy · Nov 9, 2019

https://en.m.wikipedia.org/wiki/Projectile_motion

https://en.m.wikipedia.org/wiki/Trajectory

Spoiler: It's Galileo's fault.

DanA · Nov 9, 2019

The nose will follow the path of least air resistance or air drag.

- The QB has learned to angle the ball at the optimal angle to reduce air resistance;
- The least air resistance is when the smallest surface area is affected by air resistance (nose point forward) in relation to the direction it is traveling;
- Gravity will cause the ball to deaccelerate/ accelerate at 32 feet per second.

With those three points in mind, you can understand the angle of the ball. If the ball is traveling 25 mph vertically and 25 mph horizontally then using trigonometry the optimal angle of the ball will be upwards at 45 degrees. Lets say that air resistance has slowed the ball to 20 mph horizontally at the point of catch. At this time, gravity has slowed the balls upwards movement to zero and the ball is now falling at 30 mph vertically at the point of catch. Using trigonometry we can expect the ball to be 27 degrees pointing downwards.

408Cowboy · Nov 9, 2019

DanA said:
The nose will follow the path of least air resistance or air drag.

- The QB has learned to angle the ball at the optimal angle to reduce air resistance;
- The least air resistance is when the smallest surface area is affected by air resistance (nose point forward) in relation to the direction it is traveling;
- Gravity will cause the ball to deaccelerate/ accelerate at 32 feet per second.

With those three points in mind, you can understand the angle of the ball. If the ball is traveling 25 mph vertically and 25 mph horizontally then using trigonometry the optimal angle of the ball will be upwards at 45 degrees. Lets say that air resistance has slowed the ball to 20 mph horizontally at the point of catch. At this time, gravity has slowed the balls upwards movement to zero and the ball is now falling at 30 mph vertically at the point of catch. Using trigonometry we can expect the ball to be 27 degrees pointing downwards.

You could've just said parabola to see how many people would Google it.

DanA · Nov 9, 2019

408Cowboy said:
You could've just said parabola to see how many people would Google it.

The trajectory will follow a parabola (broadly) and projectile motion will explain it's trajectory (again broadly) but technically speaking, that doesn't answer the question. Projectile motion calculations only consider gravity and gravity alone does not explain the orientation of the ball.

Tabascocat · Nov 9, 2019

DanA said:
The trajectory will follow a parabola (broadly) and projectile motion will explain it's trajectory (again broadly) but technically speaking, that doesn't answer the question. Projectile motion calculations only consider gravity and gravity alone does not explain the orientation of the ball.

You could have at least mentioned the drag coefficient in there somewhere....sheesh :facepalm:

Flamma · Nov 9, 2019

Since this seems to be the thread of odd questions, I'll post one of my own. The NFL isn't Canadian football, defenders don't have to line up a yard/meter away. The NFL has a line of scrimmage, basically a line in the sand. So how is there a neutral zone? No need to post the rulebook, I know it's defined as the length of the ball, but isn't that just off sides? Typically the tip of the ball is placed at the LOS. Any defender over the ball is obviously offsides, so why do they call it a neutral zone infraction?

The physics of a football pass

Reverend Conehead

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EST_1986

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Flamma

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EST_1986

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Reverend Conehead

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Flamma

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Reverend Conehead

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joseephuss

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408Cowboy

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DanA

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DanA

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