Dr. Dave Science

The NFL regular season is in full swing and hopefully your favorite team is showing their talent on the field. Are they Super Bowl bound? Only time will tell.

In football, one of the most exciting plays is the “Hail Mary” pass. This is when a quarterback throws the football really far (50 yards or more, that’s 45.72 meters for my metric readers) and somehow the receiver catches it.

Check out this YouTube example of Doug Flutie’s famous Hail Mary pass.

Is the “Hail Mary” muscle power or physics?

I still remember when I learned how to throw a football. At first, my throws were wobbly and the football did not travel very far. My dad showed me how to throw the ball in a spiral, and with a little practice I was throwing the ball much further.

Although I was throwing the ball with the same strength, I realized that spiraling helped the football fly better.

Naturally, I wondered “Why does spinning help a football fly better?”

Spin stabilization

By throwing a football with a spiral (no wobbles at all), the ball spins around an imaginary line that traces its path through the air (the axis of flight). This reminds me of a gyroscope.

What is a gyroscope?

A gyroscope is a wheel on an axle that spins really fast. The spinning allows it to resists external forces (like wind or sudden movements). The faster a gyroscope spins, the more stable it becomes. Take a look at these videos I found on YouTube.

Notice how this toy gyroscope stays standing while it spins, even when it is turned!

This is another cool video showing how gyroscopes resist external forces. The spinning wheel prevents it from falling over. Does this make sense?

The gyroscopes in these videos are spinning at about 200 times every second!

Did you know that gyroscopes are used in airplanes, spacecraft, and even the Hubble Space Telescope (shown below)?

In the Hubble Telescope, advanced gyroscopes are used to help determine what part of space it is pointed at. Remember, in the absence of gravity, there is no up or down!

Rockets and Artillery

When rockets were first used in combat in the 1200s, they had a tendency to veer off course. It was not until the middle 1800s when people realized that if they spun the rocket as it flew, it would fly more straight and true.

In fact this idea has also been applied to artillery. The barrel of the big guns on battleships had grooves inside them that would spin the shell when it was fired. This greatly improved accuracy of the shell as it was now less susceptible to the effects of the wind.

This is a picture of the USS Wisconsin. The guns on this ship shoot shells that are 16 inches wide!

Putting it all together – Spinning the Hail Mary

When a football spins as it travels through the air, it will fly a more stable path and be able to resist the effects of the wind. This makes the throw more accurate.

Also, the faster the ball spins, the more stable it is during its short flight from the quarterback to the receiver’s arms.

Now you know how NFL quarterbacks can throw a ball accurately!

While strength is important for providing the force behind the throw, physics plays a significant role in both distance and accuracy.

That’s cool.

-Dr. Dave