This experiment can easily be done just about anywhere.  All you are going to do here is measure as accurately as possible how the temperature of the water in an empty soft-drink bottle changes over time.  Once you have placed the water in the bottle, you can carry it to another room and take data while you do something else (perhaps your other physics assignments).  However once you start taking data, you will have to keep the bottle in a single location, the room temperature at that location shouldn't fluctuate much, and the only thing heating or cooling the bottle should be the air in the room.  You will only need to take temperature readings every 5 to 10 minutes over a period of a couple of hours.

in a typical kitchen or bathroom.  You will need the following from the lab kit:

• 250 milliliter graduated cylinder
• small plugs to stop holes
• the thermometer

WARNING:  be careful when taking the thermometer out of its case; some force might be required to take the case apart and it is possible to twist or turn the two parts of the case and break the thermometer, which is pretty fragile.  Take the same safety precautions you would with any breakable glass object.  The liquid inside the thermometer is non-toxic, but may stain clothing.

You will also need

• a clock or watch with a second hand; it you find it more convenient you can use the TIMER program, but things happen slowly in the experiment so you won't need that much precision
• a microwave oven or a stove
• a small amount of ice (a couple of cubes would suffice)
• an empty plastic soda pop or bottled water bottle (24 oz size or less works best).

Select the following option (you have only one choice):

Submitting Assignment: Temp vs. t for Water in Cup

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Look at the label of your bottle.  What brand of soft drink or bottle water is in the bottle, and how many ounces or milliliters does the bottle hold?  Indicate this information in the space below.

Your answer (start in the next line):

 

 

#$&*

 

Place the thermometer at the location where the bottle will be placed for the experiment.  Leave it there while you prepare the bottle.  The thermometer should be out of the case, and the bulb at the end of the thermometer should be elevated a bit so it is not touching anything but the air surrounding it.

Make sure your soft drink bottle is empty and ready to use.

Fill a glass about 1/2 full with cold water and add a couple of ice cubes.  Stir the water and the ice cube for a minute or so.  Then pour 50 milliliters of the chilled water into the graduated cylinder. 

Your cylinder is marked in milliliters, with number of milliliters indicated every 20 milliliters.  The small marking on the cylinder indicate intervals of 2 milliliters.

When you have 50 milliliters, give or take 1 milliliter, in the cylinder, pour the contents into the bottle.

Remove the ice cubes from the glass and leave the water in it.  Just leave it sitting while you perform the experiment.

Place the bottle in the location you have chosen.

:Before placing the thermometer in the liquid, read it carefully.  To read the thermometer accurately your line of site must be perpendicular to the axis of the thermometer.  Try to read the thermometer to the nearest quarter of a degree; it's even better if you can estimate the temperature to tenths of a degree, though you cannot expect to be completely accurate with these estimates.  With practice, though, you can read this thermometer accurately to within about .2 degrees.

Your reading will be the initial room temperature.  Write down the initial room temperature in Celsius degrees.  Also write down the time on your clock, including hours, minutes and seconds.

Enter the initial room temperature on the first line in the space below, as a decimal number.  You may then add notations or comments starting in the second line.

Your answer (start in the next line):

 

 

#$&*

 

Insert the thermometer into the bottle so its bulb is in the water. 

Stir the water with the thermometer for 2 minutes, then read the thermometer as accurately as possible.  Write down the time on your clock, in hours, minutes and seconds.

Enter the temperature in the first line, the hour on the second line, the minutes on the third line and the seconds on the fourth line of the space below.  Starting in the fifth line give a brief explanation of what your data mean.  What does this information tell you about the system (give a specific quantitative answer to this question)?

Your answer (start in the next line):

 

 

#$&*

 

Wait 5 minutes (you may do something else during the wait).  Then repeat the process of reading the thermometer and recording temperature and clock time.

The procedure for reading the thermometer is always the same:

• Stir the water with the thermometer for 2 minutes, then read the thermometer as accurately as possible.  Write down the time on your clock, in hours, minutes and seconds.
• Enter the temperature in the first line, the hour on the second line, the minutes on the third line and the seconds on the fourth line of the space below. 
• Starting in the next line give a brief explanation of what your data mean and what they tell you about the system you are observing.

Use these same steps and the same syntax for reporting your results every time you are instructed to read the thermometer, and be sure to always include your brief quantitative explanation of what the data tells.

Your answer (start in the next line):

 

 

#$&*

 

Based on your readings, estimate how long it will take the temperature to change by about another degree.  After that time has lapsed, repeat the process of reading and recording your temperature and clock time.  Don't worry if the change in temperature is a little less or a little more than a degree.  Just read everything as accurately as possible and report what you see.  Include at the end a brief (quantitative) statement of explanation.

Your answer (start in the next line):

 

 

#$&*

 

Again, after the temperature has changed about a degree, read the thermometer again and report your results in the same format as before, including a brief statement.

Your answer (start in the next line):

 

 

#$&*

 

Remove the thermometer from the water, dry it off and place it in the place it was when you originally read the room temperature.  You will read it again in a few minutes.

Unless your room is very cold, the water in the bottle would have started out below room temperature. 

• && How far below room temperature was it when you made your first measurement?  Write this number down.
• && How far below room temperature was it when you made your second measurement?  Write this number down.
• && On the average, the temperature of the water between the first and last measurements was below room temperature by an amount pretty close to the mean of the two numbers you just wrote down.  Write down the mean of these two numbers (you obtain the mean of two numbers by adding them and dividing by 2).
• && How much time elapsed between your first and last measurement of the temperature of the water in the bottle?  Write this number down.
• && At what average rate, in degrees Celsius per minute, did the temperature of the water change between the first and last measurements?  Write this number down.
• && Write down the temperature of the room, as measured by the thermometer.

You just wrote down six numbers.  Report them, one number to a line, in the first six lines below.  Starting in the seventh line give a brief explanation of what your data mean and what they tell you about the system.

Your answer (start in the next line):

 

 

#$&*

 

Now return to the glass you left sitting, and take the bottle and the thermometer with you.  Put the thermometer into the water in your glass and see what the temperature is. 

Using ice and/or lukewarm water, as needed, bring the temperature of the water to a temperature which is still below the temperature of the room in which you are doing your measurements, but which is twice as close to the room temperature as your original 50 ml sample.

Measure out 50 ml of this water.

Empty the bottle and pour the 'new' 50 ml sample into the bottle.

Return to the location at which you are making your readings. 

Repeat the procedure used previously, writing down everything as directed, with the goal of determining the time required for the temperature to change by about 2 degrees Celsius.

In the space below report your results as follows:

&&

• Line 1, room temperature at the start of your measurements.
• Line 2, the clock reading in minutes at which your first measurement was taken.
• Line 3, the clock reading in minutes at which your last measurement was taken.
• Line 4, the temperature observed in your first measurement.
• Line 5, the temperature observed in your last measurement.
• Line 6, the mean of your initial and final temperatures below room temperature.
• Line 7, the average rate at which the temperature changed in degrees Celsius per minute.
• Line 8, the temperature indicated by the thermometer, which should have been sitting for the last several minutes, exposed to the air in the location at which your are taking your readings.

As always, you may if you wish add comments and annotations starting in the line following your last line of data.

Starting in the line 9 give a brief quantitative explanation of what your data mean and what they tell you about the system.

Your answer (start in the next line):

 

 

#$&*

 

:Using your microwave oven, or if you don't have one handy using a pan of hot but not boiling water on the stove (into which you can immerse your bottle), bring the temperature of the water in the bottle to about 40 Celsius degrees above room temperature.  If you're using the microwave, heat the water in 10-second increments, checking the temperature every 10 seconds.

Repeat the entire procedure.

In the space below report your results as follows:

&&

• Line 1, room temperature at the start of your measurements.
• Line 2, the clock reading in minutes at which your first measurement was taken.
• Line 3, the clock reading in minutes at which your first measurement was taken.
• Line 4, the temperature observed in your first measurement.
• Line 5, the temperature observed in your last measurement.
• Line 6, the mean of your initial and final temperatures above room temperature.
• Line 7, the average rate at which the temperature changed in degrees Celsius per minute.
• Line 8, the temperature indicated by the thermometer, which should have been sitting for the last several minutes, exposed to the air in the location at which your are taking your readings.

Starting in the line 9 give a brief quantitative explanation of what your data mean and how they compare to similar data taken under previous conditions.

Your answer (start in the next line):

 

 

#$&*

 

Repeat again, this time starting about 15 degrees Celsius above room temperature, and report below in the same format specified previously, being sure to include your brief commentary in line 9:

Your answer (start in the next line):

 

 

#$&*

 

Finally, again starting about 15 degrees Celsius above room temperature, repeat the experiment for a 100 milliliter sample of water and report below, in the same format as before, being sure to include commentary:

Your answer (start in the next line):

 

 

#$&*

 

:If you had two identical 50-milliliter samples in identical bottles, but one was 10 degrees Celsius below room temperature and the other 5 degrees Celsius below room temperature, which would you expect to approach room temperature more quickly, or would they approach at the same rate? 

&& How much more quickly would the faster-changing sample change?

Support your conclusion with an explanation based on results from your experiment.

Your answer (start in the next line):

 

 

#$&*

 

If you had a 50-milliliter sample and a 100-ml sample in identical bottles, both 10 degrees Celsius above room temperature, which would you expect to approach room temperature more quickly, or would they approach at the same rate? 

How much more quickly would the faster-changing sample change?

Support your conclusion with an explanation based on results from your experiment.

Your instructor is trying to gauge the typical time spent by students on these experiments.  Please answer the following question as accurately as you can, understanding that your answer will be used only for the stated purpose and has no bearing on your grades: 

• Approximately how long did it take you to complete this experiment?

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