Field Goal! The Science Behind a Perfect Football Kick
QTY
ITEM DESCRIPTION
1
Catapult with locking pin
1
Clamp for attaching catapult to table
1
Ping pong ball
1
Light plastic ball with holes
3
Rubber band, 3" x 1/8"
Figure 1. A football needs to follow a certain trajectory for a player to make a successful field goal. To score points, the
player must send the ball between the goalposts. If the ball does not go far enough (the kick is "short"), or if the ball goes
to the left or right of the goalposts instead of between them (the kick is "wide"), then the field goal does not count.
Summary
Prerequisites
None
Safety
Never launch projectiles at people, animals, or anything fragile. Be careful not to get your
fingers caught in moving parts of the catapult.
However, not every pass or kick is perfect. It can be hard to concentrate when you have a 300 pound linebacker running
at you full speed! There are many factors that can affect whether or not a field goal is good, including how the ball is held
in place for the kicker, weather conditions like wind and rain, and how far the ball is from the goalposts. If you watch a lot
of football, you have probably noticed some of these things. In this sports science project, you will test just one of these
variables: distance. You will set up a rubber band-powered catapult to act like a kicker's leg, and use it to kick field goals
with a small toy football. You will adjust the distance between the kicker and goalposts, and see how accurately you can
kick field goals at each distance. How do you think your accuracy will change as you move farther and farther away?
http://www.sciencebuddies.org/science-fair-projects/project_ideas/Sports_p059.shtml#help
Terms and Concepts
Frequently Asked
Questions
Projectile motion
Gravity
Air resistance
Trajectory
Abstract
Did you know that throwing, kicking, and punting a football all involve the science of projectile motion? A star NFL®
quarterback, kicker, and punter each need to have a very good understanding of how a football moves through the air in
order to help them win games. In this science project, you will set up a rubber band-powered catapult to represent a field
goal kicker, and study how changing the distance from the goalposts affects how hard it is to accurately kick a field goal.
Objective
Use a rubber band catapult kit and a toy football to kick field goals and see how your success rate varies with distance.
Introduction
Have you ever seen a National Football League (NFL®) game with an exciting, game-winning touchdown pass or field
goal? Believe it or not, there is actually a good deal of physics behind those passes and kicks. The science of how an
object (like a football) moves through the air when it is launched, kicked, or thrown is called projectile motion. Projectile
motion tells you how forces like gravity and air resistance affect the path an object follows when it moves through the
air, also called its trajectory. To land in a receiver's hands or pass through the field goalposts, the football needs to follow
a specific trajectory, as shown in Figure 1, below.
Questions
How does gravity affect a football (or other projectile) as it moves through the air?
How does air resistance affect a football (or other projectile) as it moves through the air?
What happens in real NFL games—are kickers more or less likely to miss when they attempt field goals from
farther away?
What do you think will happen to your field goal percentage as you move farther away in your experiment?
Can you look up the kicking statistics for your favorite team's kicker? How many field goals do they attempt, and
make, at different distances?
Are there any limits on the trajectory of a real football? For example, what is the longest NFL field goal record?
Bibliography
Here are some additional references about the physics of football:
Time Warner Cable's Connect a Million Minds. (2013). Football Learning Guide for Parents and Educators.
Retrieved October 29, 2013, from http://www.connectamillionminds.com/assets/media/sis/downloads/football.pdf
(http://www.connectamillionminds.com/assets/media/sis/downloads/football.pdf)
Time Warner Cable's Connect a Million Minds. (2013, May 24). STEM in Sports: Victor Cruz PSA. Retrieved
October 29, 2013, from http://youtu.be/cgCKDCVC2vM (http://youtu.be/cgCKDCVC2vM)
Shipman, M. (2013, September 20). Wide left: study shows that holders play key role in field goal accuracy.
Retrieved November 14, 2013, from http://phys.org/news/2013-09-wide-left-holders-key-role.html
(http://phys.org/news/2013-09-wide-left-holders-key-role.html)
Here is the official 2013 record book for the NFL, which contains information about various field goal records:
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National Football League. (2013). Official 2013 National Football League Record & Factbook. Retrieved October
29, 2013, from http://seahawksmedia.com/RecFactBook/FactBook2013.pdf
(http://seahawksmedia.com/RecFactBook/FactBook2013.pdf)
You can use this page to look up statistics about different players and their field goal percentages at different distances:
ESPN. (2013). NFL Player Kicking Statistics—2013. Retrieved November 11, 2013, from
http://espn.go.com/nfl/statistics/player/_/stat/kicking/sort/fieldGoalsMade
(http://espn.go.com/nfl/statistics/player/_/stat/kicking/sort/fieldGoalsMade)
This is a general reference about projectile motion:
The Physics Classroom. (n.d.). Projectile Motion. Retrieved October 29, 2013, from
http://www.physicsclassroom.com/class/vectors/u3l2a.cfm (http://www.physicsclassroom.com/class/vectors/u3l2a.cfm)
Experimental Procedure
Set Up Your Experiment
1. In this section, you will set up your experiment like the setup in Figure 2, below. Read the steps below for detailed
directions.
Figure 3. The catapult, rubber band, and pin (top left). Use the pin to lock the metal disc in place relative to the base of
the catapult (top right). Loop a rubber band through the large hole in the metal disc, and hook it on both sides of the pin
sticking through the launch arm (bottom left). The assembled catapult (bottom right).
3. Clamp your catapult to a piece of furniture.
a. Use a clamp (either the spring clamp that came with the catapult kit, or a C-clamp; a C-clamp will probably
work better) to clamp your catapult hanging upside-down from a piece of furniture, like a table or a desk, as
shown in Figure 4, below.
b. Remember that you may need to move around some furniture in your house to have enough room for the
experiment. Make sure you have at least 4 or 5 meters (m) of open space in front of the catapult.
i. Note: In NFL games, distances are measured in English units: yards, feet, and inches. However,
scientists always use metric units, so for your science project, you should always measure distances
in meters.
c. Important: If you do not watch to scratch the furniture, use paper towels or a small dish towel as padding
between the furniture and the clamp.
Figure 2. The experiment setup for this science project.
2. Set up your catapult.
a. Get the catapult, metal pin, and a single rubber band from your catapult kit, as shown in the top left picture
of Figure 3, below.
b. Push the pin through the hole in the base of the catapult (the black part) to lock the circular metal disc in
place, so the 45 on the disc is showing just below the black bar (see Figure 3, top right). Notice that the
metal disc has multiple holes, so you have to push the pin through the correct hole to line up the 45.
i. Note: This pin sets the "follow-through angle", or how far the catapult arm will keep moving after it
makes contact with the ball. For this experiment, you will keep the follow-through angle constant. If
you want to find out what happens when you change this angle, see the Make It Your Own
(http://www.sciencebuddies.org/science-fair-projects/project_ideas/Sports_p059.shtml#makeityourown) tab.
c. There is a large hole in the top of the metal disc. Push a rubber band through this hole and hook it on both
sides of the pin that sticks through the catapult's launch arm (see Figure 3, bottom left).
d. When you are done, the assembled catapult should look like the bottom right image in Figure 3.
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the farthest distance and gradually move the catapult closer.
b. Ideally, you should set your goalpost up 5 m from the catapult. If you go much farther than that, you may go
out of the catapult's range. If you do not have that much space available, you may need to start with the
catapult closer.
6. Set up your kicking tee.
a. Use something like a medicine cup or a small bottle cap as a kicking tee (see Figure 6, below).
b. Using a stack of cardboard boxes or books, as necessary, set up your kicking tee so the ball is at just the
right height to be "kicked" by the end of your catapult arm when it swings (see Figure 7, below). The exact
height of boxes/books that you need will depend on the height of the furniture you clamped your catapult to.
Figure 4. Catapult clamped to the bottom edge of a workbench.
4. Build your goalpost.
a. Use household materials like cardboard and duct tape to build a goalpost that is roughly 0.3 m wide, like the
one shown in Figure 5, below. The exact size of your goalpost does not matter for this science project; just
make sure it is a reasonably sized target for your toy football.
Figure 6. A medicine cup or small bottle cap will work as a kicking tee.
Figure 5. This goalpost is made from cardboard, duct tape, and a small trash can.
5. Set up your goalpost in front of your catapult.
a. Set up your goalpost as far as possible from the catapult. When you do the experiment, you will start out at
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Figure 7. This picture shows a textbook and two cardboard boxes used to adjust the kicking tee to the appropriate height
for the catapult.
Kick Some Field Goals!
1. Make a data table like Table 1, below.
a. Note: Depending on the amount of space you have to work with, you may have to adjust the distances in
the first column. Try to make sure you test at least four different distances.
i. For example, if you only have 4 m of total space, you could test distances of 1, 2, 3, and 4 m.
ii. If you have more space available, you could test 1, 2, 3, 4, 5, and 6 m.
you are using an exact replica of Table 1, you should put your goalpost 5 m away from your catapult.
3. Take some practice kicks to get used to using the catapult setup.
a. Use one hand to pull the arm of the catapult back, while you carefully place the football in the kicking tee
with your other hand.
b. Move your free hand out of the way once you have placed the ball, so you do not hit your fingers!
c. Let go of the catapult arm; it will immediately swing forward and hit the football. Did it go through the
goalposts? If so, you scored a field goal!
d. If the ball did not go through the goalposts, you may need to make some adjustments to your catapult
setup. This part will take some trial and error, depending on how far off your first kick was. There are
several different things you can try to help aim your kicks:
i. If the ball did not go far enough (the kick was too weak), you can add more rubber bands to your
catapult. Your catapult kit came with three rubber bands. Try adding one or two more rubber bands
the same way you attached the first one. This will make each "kick" stronger.
ii. You can also adjust how far back you pull the catapult arm before releasing it. The farther back you
pull the arm, the more it stretches the rubber band, so the harder it will kick the ball.
iii. If the ball is going too high or too low, try adjusting the height or the forward-backward position of
your kicking tee slightly. This will change where, during the swing, the catapult comes into contact
with the ball, which will affect how high or low it is kicked.
iv. If you are missing field goals wide left or wide right, try adjusting the left/right position of the tee
slightly. This can affect whether the ball goes straight or hooks to the side.
e. Once you have found a good setup to kick field goals, you need to record the settings you are using to
make sure you can do repeated trials.
i. Pay attention to how far back you pull the catapult arm. You can do this by reading the angle
markings printed on the metal disc on the catapult. For all future trials, make sure you pull the
catapult arm back to the same spot. This will ensure the ball always goes far enough.
ii. Pay very close attention to exactly where you place the kicking tee, as this can have a big impact on
where the ball goes. It may help to tape down a piece of paper and draw a box around the kicking
tee, to make sure you can put it back in the exact same place each time.
iii. If necessary, use duct tape to secure the pile that is holding up your kicking tee (for example, if you
are using three cardboard boxes, tape them together so they do not shift around after each kick).
4. When you have completed your practice kicks, take 25 official kicks to calculate your field goal percentage at this
distance.
a. Use your data table to record your total number of successful field goals and your total number of attempts.
b. If you have time, you can collect more data and try more attempts (for example, 50 attempts at each
distance).
5. When you have completed all of your kick attempts at this distance, calculate your field goal percentage using
Equation 1, below, and enter it in the third column of your data table:
Equation 1:
a. For example, if you attempted 25 field goals but only made 17 of them, your field goal percentage is:
Distance (m)
Field Goals Made
Field Goal Attempts
Field Goal Percentage
1
2
3
4
5
Table 1. A data table to keep track of your field goal kicking. Remember that in NFL games, distances are measured in
yards, but for your science project, you should use metric units and measure in meters (m).
Equation 2:
6. Move your goalposts to the next closest distance from your data table (for example, move them from 5 m to 4 m),
then repeat steps 4–5 for this new distance.
a. Do not change how hard you kick the ball. Keep the number of rubber bands and how far back you pull the
catapult constant. Technically, this is different from real football (a kicker would not need to kick a 10-yard
field goal as hard as they would need to kick a 60-yard field goal). But, since you are doing a controlled
experiment, you want to make sure you do not introduce any extra variables.
b. You can still take a couple practice kicks before you start taking data at the new distance.
c. Remember to record the results in your data table.
7. Make a graph of your data with field goal percentage on the vertical axis (y-axis) and kick distance on the
horizontal axis (x-axis).
a. If you need help creating a graph, you can use the Create a Graph (http://nces.ed.gov/nceskids/CreateAGraph/default.aspx)
website.
8. Analyze your results. How does field goal percentage vary with kick distance? Did it get harder or easier to kick
field goals as the goalposts got farther away? How do your results compare to your hypothesis?
2. Double check to make sure your goalpost is set up at the farthest distance from your data table. For example, if
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Variations
Ben Finio, PhD, Science Buddies
If you watch football games or play football yourself, you have probably noticed that real kickers follow through with
their leg when they kick the ball. You can use the pin that locks the metal disc to the catapult's base to change the
"follow-through" angle of the catapult arm. The pin determines where the catapult arm stops, which controls how
far it will keep moving after it initially makes contact with the ball. Try a new experiment to measure how changing
this angle affects your field goal percentage.
Use a tape measure to measure how far the football goes when you:
pull the catapult arm back to different angles
change the follow-through angle (as described in the previous variation)
use a different number of rubber bands.
NFL kickers wear special shoes designed just for kicking. In this science project, you just used the cup at the end
of the catapult arm as a "shoe." Explore how the size, shape, and material of the "shoe" affects the ball's trajectory.
For example, what happens if you tape a flat piece of cardboard over the cup instead?
What happens if you change the tee position? Create a science project to measure how the tee position affects the
trajectory of the ball. Is there an optimal tee position to get the best field goal percentage?
NFL is a registered trademark of The National Football League.
Wiffle is a registered trademark of The Wiffle Ball, Inc.
Last edit date: 2014-01-03
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by the FAQs on our site. Please email us at [email protected] (mailto:[email protected]?
subject=Field%20Goal!%20The%20Science%20Behind%20a%20Perfect%20Football%20Kick)
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Questions for this PI at http://www.sciencebuddies.org/science-fair-projects/project_ideas/Sports_p059.shtml#help
In your email, please follow these instructions:
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Credits
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