Events
for the 2013 Western Kentucky Physics Olympics
Judges
determine the overall winner based on each team's score in the five different
events.
- Bouncing Polymers: the Do-Ahead Project
- Carbonated Geysers: the Plan-Ahead Competition
- Molecular Isomers: the Calculation/Communication Challenge
- Inertial Challenge: the Impromptu Team Physics Activity
- Fermi Questions – the Order-of-Magnitude Quiz
Do-Ahead Event:
Bouncing Polymers
The object of this Do-Ahead Project is to make a bouncing ball from
household ingredients. Once you understand the basic technique, you can alter
the recipe for the ball to see how the chemical composition affects the
bounciness of the ball. Here's a list
of materials you need to gather to make bouncing polymer balls:
- timer
- 2
containers for mixing
- measuring
spoons
- spoon
or craft stick to stir the mixture
- warm
water
- borax
(used for laundry)
- cornstarch
(used for baking)
- school
glue (e.g., Elmer's)
Pour 2 tablespoons warm water and 1/2
teaspoon borax powder into the first cup. Stir the mixture to dissolve the
borax.
Pour 1 tablespoon of glue into the
cup labeled 'Ball Mixture'.
Add 1/2 teaspoon of the borax
solution you just made and 1 tablespoon of cornstarch. Do not stir.
Allow the ingredients to interact on their own for 10-15 seconds and then stir them together
to fully mix.
Once the mixture becomes impossible
to stir, take it out of the cup and start molding the ball with your hands. The
ball will start out sticky and messy, but will solidify as you knead it.
Experiment with the ratio between the amounts of glue,
cornstarch, and borax. You can also vary the diameter of the finished ball, how
long it takes to solidify into a ball. The goal is to create a ball that
bounces high when dropped from a height of 2 meters.
Don't eat the materials used to make
the ball or the ball itself. Wash your work area, utensils, and hands when you
have completed this activity.
1. Each team may bring one ball to the
competition for judging.
2. Each team’s bouncing polymer ball will be inspected by
the judges to ensure it was made from the listed ingredients.
3. Rankings are determined by the height in
centimeters that the ball reaches when rebounding off of a concrete floor after
being dropped from a height of 2.00 meters.
4. All contestants will ensure that their
entry works through the application of physics principles and generally follows
the spirit of the competition.
Plan-Ahead Event: Carbonated
Geysers
The year’s Plan-Ahead competition
requires teams to construct and demonstrate carbonated beverage soda fountains
in two contests.
When a Mentos candy is dropped into a
bottle of soda, an impressive geyser-like eruption is created. This is
a physical reaction, not a chemical reaction. The vigor of the geyser depends
on various factors that affect the growth rate of carbon dioxide bubbles. In a
carbonated beverage, dissolved carbon dioxide gas forms bonds with the water
and surface tension helps keep the bubbles of gas suspended in the liquid. The
rough surface of the Mentos candy creates more surface area and more rough
edges to promote a much more abrupt release of bubbles. Foam is rapidly created when the pitted
surface of the Mentos allows the gelatin and gum arabic
in the candy to come into contact with the CO2 gas in the carbonated
beverage. Foaming is maximized in diet soda by the artificial sweetener affecting
the surface tension. Details of the reaction have been published in a June 2008 article in the American Journal of Physics,
"Diet Coke and Mentos: What is really behind this physical reaction?"
(Coffey, T., American Journal of Physics 76(6):
551–557).
1.
Soda fountains may be created using any commercially available soda sold in a 2
L or smaller plastic bottle. Teams must provide their own unopened soda for the
competition. Every bottle of soda must be presented to the judges to ensure
that it is factory sealed and unaltered at the beginning of each contest.
2. Only physical nucleation may be used
to induce the fountain. Chemical
reactions, physical shaking, heating, and sonication are not allowed. The soda
bottles may not be externally pressurized prior to or during the competition.
3. Teams must provide their own
nucleation material. There is no limit to the form or amount of nucleation
material a team can add to the 2-liter bottle of soda.
4. Bottles and caps may be modified in anyway to
effect introduction of the nucleation material and subsequent soda fountain
direction or shape.
5. In the bucket filling contest, the container used to catch the geyser's output will have at least a 0.25m opening, be tipped toward the launch area at an angle of 30 degrees from the vertical, and will have it's front edget 4.0 meters away from the end of your nozzle. Bottles may be placed on stands or in
holders as part of the competition.
6. Each
team will be allowed three trials, to be divided as they choose between the
bucket filling contest and the height contest. All three trials may be used for
one contest, with a score of zero assigned for the contest with no trials.
7.
The bucket filling contest score is computed as the number of milliliters
captured in the target, measured to the nearest 5 milliliters.
8. The
height contest score is computed as the number of centimeters achieved by the
highest visible bit of soda foam, measured to the nearest 5 centimeters from the
top of the nozzle.
9. Rankings
for the competition will be based on the greatest total achieved by each team.
10. All team members must wear splash proof safety goggles during the
competition and shall
ensure that their entry works through the application of physics principles and
generally follows the spirit of the competition.
Event 3: Molecular
Isomers – Communication/Calculation Challenge
Your
team will be given basic information about molecular isomers then asked to
divide into two groups. Two members of the team will devise a
step-by-step strategy to transform a given molecule into a particular isomer.
The remaining two team members will be presented with
the created set of instructions and with no additional communication will be
required to use the provided parts to construct the specified isomer.
Event 4: Inertial Challenge – Impromptu Team
Activity
Activity is the key word for this competition, with the goal being for each team to achieve the desired result as quickly as possible. The situation is designed to reward teamwork and common sense thinking as well as knowledge of physics. Every team will come away with smiles and good memories regardless of how well they master the particular challenge.