That sounds like a fantastic project! Here
are my answers to your questions.
1. What is your career choice?
I am a research scientist. Currently, my
research project involves studying solar
2. How would I find the starting temperature
of the cooler?
To measure the initial temperature of the
cooler, use a thermometer or a thermocouple.
Make sure you leave the thermometer in the
cooler long enough to get a stable measurement.
It may take a few minutes before the temperature
reading stops fluctuating, depending on the type
of instrument you use.
I have several suggestions that will make the
a. Use the same amount of ice in each cooler.
Also make sure the water and salt water start
out at about the same temperature before you add
them to the ice.
b. Make sure the beverages all start at the same
temperature and use the same volume of each
c. Keep the beverages all in the same type of
container, unless you are also interested in
seeing how the container affects the beverage
temperature. Heat transfers faster through metal
cans than glass bottles, for example.
d. You can define how fast the beverage cools in
two ways. (1) Which beverage reaches the coldest
temperature after a set amount of time or (2)
which beverage cools to a set temperature in the
least amount of time. You can determine both by
measuring the temperature every few minutes so
you can create a graph of temperature versus
time for each beverage in each different cooler.
If possible, I suggest leaving the thermometer
or thermocouple in the beverage as it cools for
ease of measurement.
e. It may be simpler to start with just one type
of soda and one type of milk for your first
measurements. With only two beverages, you will
still have to do 6 experiments to test all of
the cooler conditions. I expect the results will
be similar for coke and sprite and for cow milk
and goat milk.
f. Overall, try to be as consistent as possible
with all of you experimental procedures. Be sure
to write down exactly what you do for each
experiment so you can repeat the same steps in
the next one.
3. What do you think will happen? Why?
I think the cooler with ice will cool the
beverages the fastest and I think the milk will
be cooled faster than the coke and sprite.
The cooling rate will depend on how rapidly
heat can transfer from the beverage to the
surrounding material. Heat can transfer by three
means: conduction, convection, and radiation.
Conduction will occur when heat from the
beverage transfers to the surrounding material
by the vibrations of the atoms touching each
other. Convection will occur as the warmed fluid
(either air, water, or salt water) near the
beverage moves away and colder fluid moves in.
Radiative heat transfer occurs when heat is
emitted as electromagnetic radiation, but this
mechanism will not be very important for a room
temperature beverage. (Radiative heat transfer
is more important for hotter substances like
white hot metal or stars which emit heat through
Because the water will be in better direct
contact with the beverage container than the
ice, which will have air gaps between it and the
beverage container in some places, I expect the
water will have better conduction than the ice.
Also, since the water is a fluid, convection
will help move some of the heat away from the
beverage. Therefore, I think both conduction and
convection will be more efficient for the ice
water than for the ice alone. I expect the salt
water will be even more effective than the plain
water because in addition to having good heat
transfer like water, it will also be colder than
the water. This is important because heat flows
from hot to cold, and it transfers faster when
there is a larger difference in temperature.
Salt water freezes at a lower temperature than
fresh water so the salt water will melt the ice
faster allowing the salt water to get colder
faster, and therefore cool the beverages faster.
It is important to note that even though the
salt water cools faster, at equilibrium (when
all of the ice is melted and mixed with the
water) the water and salt water will be at about
the same temperature (assuming the same starting
quantities and temperatures are the same). The
difference is that the salt water will melt the
ice faster, which makes the water colder faster,
which will cool the beverages faster.
I expect the milk will cool faster than the
soda because milk has a lower latent heat
capacity than water (3.93 J/gK for milk vs. 4.19
J/gK for water), meaning that milk holds less
heat than the water. However, the heat transfer
depends on the thermal conductivity and density
as well as the latent heat capacity of the
beverage, so my prediction may be too
simplistic. Also, I am not sure how or if the
sugar and ions in the soda will change its
latent heat capacity.
Please feel free to send additional questions
if you are curious about the thermodynamics of
heat transfer or have more questions about your
4. What do you have your credentials in?
I have a Bachelor’s of Science (B.S.) degree in
Chemistry and I am currently in a Ph.D. program
studying Materials Science and Engineering.
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