Sports Science: Football

The fourth Thursday in November is the perfect time to spend time with family, eat some home-cooked comfort food, and watch grown men throw around an inflated pig bladder.

That’s right, folks; the world’s first American football was actually an inflated pig bladder, hence the nickname “pigskin.” Don’t worry, modern footballs are made of leather or vulcanized rubber, but the shape of a football remains the same as it’s ever been, lending itself to an interesting discussion of physics.

My sophomore year of college at Washington University in St. Louis, my physics professor’s lecture the week of Thanksgiving featured two balls, a red rubber kickball and an American football. She asked us to predict how the balls would bounce. The spherical kickball was easy; the American football was not.

Football shape

The ovoid shape combined with the two sharp points at each end mean that the ball can bounce in just about any direction at any angle depending on its orientation as it is falling and what part of the football makes contact with the ground. That’s why every football coach I ever had drilled us on just falling on the ball instead of trying to catch it or scoop it up; it is extraordinarily difficult to predict just which way the ball will bounce! These bounces often manifest on plays when a bouncing ball is live, like a fumble, an onside kick or following a punt.

As the game evolved, so did the football itself. As you can imagine, inflating animal bladders can be inconsistent; now, the NFL football is standardized at about 11 inches long from tip to tip and a circumference of about 28 inches around the center. Those bladders could also be difficult to grip, so the modern football has a coarse, pebbled texture as well as white laces in the center.



Because of its shape, the football cuts through the air most easily when spinning around its longest axis, called a spiral. This spiral minimizes air resistance and allows the ball to move in a more predictable parabolic motion.

A common misconception is that the spiral motion allows the ball to travel farther, but this idea falls apart with basic physics. When a ball is initially thrown, there is a set quantity of total energy in the system. That set amount cannot be increased or decreased, just changed from one form to another according to the Law of Conservation of Energy. The spinning motion of a football in the air requires kinetic energy, so every Joule of kinetic energy required to keep the ball spinning is less energy dedicated to the football’s motion.

Instead, the spiral is important because of a concept called angular momentum. A spinning football behaves like a gyroscope; a ball will maintain roughly the same orientation while travelling. This makes the football’s movement from point to point easier to track and predict for a player.step0So when tossing around the ol’ pigskin Thanksgiving Day, make sure you grip the ball with the laces as you throw! What works best for me is to put my middle finger, ring finger and pinkie finger on alternating laces at the front of the ball (as pictured above).

When throwing a football, it is important to generate the force for the ball from your legs. If you are right-handed like me, stand sideways with your right leg behind you. Push off against the ground with your back leg and turn your body to throw as you do so. Bring the football backwards and then forwards over your shoulder, allowing the ball to roll off of your fingers straight. No need for any wrist twisting, as the ball should naturally move in a spiral. (See proper form below.)step1Step one: feet shoulder width apart, hands meet on the ball.step2Step two: weight on your back foot, bring the ball back, wrist out.step3

Step three: throw the ball, wrist in. Allow the ball to roll off of your fingers, but keep your wrist straight and stable. Release the ball over your shoulder. Remember, it’s not a baseball. step4Step four: follow through after the release.

Whether you’re facing the New Orleans Saints or the neighbors across the street, the principles of physics are crucial to your football team coming out on top. May the forces be with you! Happy Thanksgiving!

We’ve Got the Fever: Particle Fever screening one night only at HMNS! (10/9/14)

Next week we’re bringing you the chance to glimpse back in time to the very beginning of the universe with the critically acclaimed documentary Particle Fever screening Thursday, October 9 in the Wortham Giant Screen Theatre at 6:00 p.m.

“Wait a second,” you might say, “how can this documentary show us the beginning of the universe? I’m pretty sure cameras came along much later.”

Well what if I told you that scientists have built a machine capable of re-creating the conditions of that very, very, very, very hot, small, energetic place that would eventually come to be the universe as we know it.

Along the way these scientists also invented a handy little thing called the internet (sorry, Al Gore). You might’ve heard of it… No? Google it.

These are the scientists at CERN in Switzerland and over the past several decades they’ve designed and built the Large Hardron Collider, which is the biggest machine ever made. 

“The large whaaaaaa?”

It’s basically a 5 story tall, 27 kilometer long tunnel, lined with computers, 100 meters underground capable of making particles collide with one another at extremely fast speeds so they break up into their fundamental pieces. This can give us a better idea of why the universe looks and behaves the way it does. 

In this exciting, fast-paced documentary we get a front-row seat to the frontier of scientific discovery. We watch as scientists’ entire careers hang in the balance, waiting to see what will come out of these experiments. Told through interviews and stunning animation, in a very “approachable-and-interesting-even-if-you-failed-high-school-physics” way, this film will inspire you, much like the scientists it features, to seek out every answer you can about the “everything there is” — the universe.

Don’t miss out!

Particle Fever, showing October 9 in the Wortham Giant Screen Theatre at 6:00 p.m.


Watch the video below for a fantastic intro to the experiments at CERN:


This video delves a little further into just why these scientists are so bent on discovering new particles:

Film Screening
Particle Fever Film Screening
Thursday, October 9, 6 p.m.

Join Hadron Collider researcher Dr. Paul Padley of Rice University for this one-night-only screening of the film Particle Fever at HMNS. Click here for tickets.

Google gets it. Celebrate Léon Foucault’s 194th birthday by sharing your swinging HMNS memories!

If you’ve yet Googled today, you may have noticed a lovely homage to Léon Foucault, the famous French physicist best known for inventing the Foucault pendulum (that ever-popular swingy thing at HMNS).

The Foucault Pendulum gets the Google Treatment!

The Foucault Pendulum has long been one of the most memorable areas of the Museum, even if some people (this girl) lack the patience to actually watch the pendulum kick over a peg.

When a peg does go over, there are inevitable cheers. As the pendulum swings, it moves clockwise with the Earth’s rotation, knocking over one peg approximately every 15 minutes. Although the pendulum appears to be traveling around the circle, it’s actually the earth that moves, making this exhibit a perfect visualization of the earth’s rotation.

(Foucault himself said it a little less simply, like this: T = 24/sin q where T equals the amount of time to make one complete revolution and q is the latitude of the pendulum.)

We scoured the interwebs (as we are wont to do) to gather some of our favorite photos of patrons standing enrapt around the pendulum.

Have your own photos or memories to share? Hit us up on social media!

Educator How-To: The magic of magnetic fields

What better way to understand how magnetic fields work than to see them for yourselves?

•    Magnetic field line cards (green) – one per child
•    Magnetic nail polish
•    Clear nail polish
•    Assorted magnets of various shapes and sizes
•    Large clear glass playing pieces
•    Button magnets (at least ½ inch)
•    E-6000 or other silicone glue

1. You will need to purchase some magnetic field viewer cards. They are sturdy and fairly inexpensive, so a single class set will last you a while. (You may also choose to just buy the magnetic film and make your own cards, but it doesn’t have the explanation printed on it.)

Educator How-To: Magnetic Field Magnets

2. Pass out a magnet and a magnetic field viewing card to your students. Try the magnets with the field line cards. What looks the same, what’s different? How do you think the field line cards work? [See the magnetic field viewer cards for more explanation.]

Educator How-To: Magnetic Field Magnets

3. Have the students trade their magnets around and see how the various shapes and sizes of the magnets affect the field viewer.

Educator How-To: Magnetic Field Magnets

4. Give each student a glass piece and place it on the table with the rounded side down.
5. Paint a thin coating of clear polish on the flat surface.

Educator How-To: Magnetic Field Magnets

6. Paint a reasonably thick coating of magnetic nail polish on the flat side of the piece. (Don’t shake your fingernail polish if it has been sitting on a shelf for a while. Instead roll it back and forth in the palm of your hands.)

Educator How-To: Magnetic Field Magnets

7. Quickly (there’s only a small window of time for this) use magnets to create a design now that you know what the magnetic fields will do to the nail polish! You want to put the glass playing piece and the magnets as close as possible without touching one to the other.

Educator How-To: Magnetic Field Magnets

8. Do not pick this up for a few minutes, and allow it to dry.
9. Once dry, use a silicone glue to attach a ceramic button magnet.

Educator How-To: Magnetic Field Magnets

10. Now use your magnets to hang up masterpieces, papers with no name and missing homework!

Educator How-To: Magnetic Field Magnets

How do magnets work?

Questions that often come up are, “How do magnets work?” or “Why is iron magnetic? or “What makes a magnet?” or “What is the magnetic field made of?”

Those are good questions, and they deserve a good answer. However, there is a lot about magnets at the atomic level that isn’t known yet. Just like with most of the other basic forces we are familiar with, such as gravity, electricity, mechanics and heat, scientists start by trying to understand how they work, what they do, whether there are any formulas that can be made to describe (and thus predict) their behavior so we can begin to control them, and so on.

The work always starts by simple observation (that’s the fancy word for playing around with the stuff!) That’s why it’s so important to have some hands-on experience with magnets.

Have your students take two magnets and tried to push like poles together. How far away do you start to feel the repulsion? How does the force vary with the distance between them? When the magnets are moved off-axis to each other (moving them to the side and not head on) what does it feel like? Could you describe it like trying to push two tennis balls together? When you flip one around, what changes? What about moving one around the other in a circle?

Encourage your students to try these things; that’s how you learn! Only when they play with magnets will they begin to understand how they work. This is the stuff great scientific pioneers did, like Faraday, Lenz, Gilbert, Henry and Fleming.

What we can find out through play are some of the basics of magnetism, like:

•    The north pole of the magnet points to the geomagnetic north pole located in Canada above the Arctic Circle.
•    North poles repel north poles
•    South poles repel south poles
•    North poles attract south poles
•    South poles attract north poles
•    The force of attraction or repulsion varies inversely with the distance squared
•    The strength of a magnet varies at different locations on the magnet
•    Magnets are strongest at their poles
•    Magnets strongly attract steel, iron, nickel, cobalt, gadolinium
•    Magnets slightly attract liquid oxygen and other materials
•    Magnets slightly repel water, carbon and boron