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Introduction:

This lab exercise is designed to provide you with experience in formulating scientific hypotheses, creating experiments, collecting data, testing your hypothesis, and interpreting your results.  Answer all questions directly on this lab worksheet and then upload your answers via the ACE Assignments Tool.

Materials

You will need the following items to complete this lab.

1. A standard 6 to 12 oz cup for holding water
2. Water
3. A refrigerator (optional)
4. A thermometer for measuring liquids
5. A timer or clock
6. Microsoft Excel or comparable open source spreadsheet program

Observation—Statement of the Problem.

1. The first part of the Scientific Method is making observations. For this assignment you can choose to make your observations inside or outside, but if you choose the outside make sure you do so on a clear, sunny day without rain.  If you make them inside you will need a refrigerator.

We all know that placing objects in the sun makes them warmer and placing them in the refrigerator makes them cooler.  But how much warmer?  And how much cooler?  This experiment is designed to help us find out.

If you wish to conduct this experiment indoors, think about your past experience with your refrigerator.  Once you bring home a gallon of milk or a can of soda from the store, how long does it take for it to cool off in the fridge?  Create a hypothesis that relates length of time in the refrigerator to drop in temperature of a liquid.  Your hypothesis should look sometime like:  Water placed in an open container in my refrigerator will decrease in temperature by 100 degrees F in 1 hour.

If you wish to conduct this experiment outdoors, think about your past experience with objects placed in the sun.  How long does it take for water to heat up when in direct sunlight?  Create a hypothesis that relates length of time in the sun to increase in temperature of a liquid.  Your hypothesis should look sometime like:  Water placed in direct sunlight in an open container will increase in temperature by 100 degrees F in 1 hour.

Gather Data.

1. Now, take your cup (open container) and fill it with tap water from your sink or a water fountain. Take your thermometer and measure the starting temperature of the liquid and write this measurement in Time O below.  Then place the cup of water either in the refrigerator or in direct sunlight outdoors and collect temperature measurements for each time interval listed in the table (1 minute through 1 hour/60 minutes).

 Time (min) Temperature 1 0 2 1 3 5 4 10 5 15 6 20 7 25 8 30 9 40 10 50 11 60

Analyze the Data.

1. Use Microsoft Excel to graphically depict your data as a scatter plot. To do this, enter the time and temperature data from the above table into Excel.  Then highlight the data and click the Insert tab, then select Scatter from the Charts options.  Choose the first scatterplot option (Scatter with only Markers).  Once you have your scatterplot, add a trendline and equation on the plot by right clicking on one of the data points and selecting Add Trendline.  Select either exponential or linear from among the options based on which you feel best matches your data.  Then select Display Equation and Display R-squared from among the options at the bottom of the dialog box.  Rearrange the equation and r-squared value so that the scatterplot looks nice with no information overlapping.

Describe the pattern of the data:  Are time and temperature related variables?

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1. Do your data support your hypothesis? Why or why not?   What alternate explanations could account for your data?  What other tests might you run or how might you better improve this test to more completely evaluate your hypothesis?

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1. Should you accept, modify, or reject your hypothesis? Why or why not?

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1. What has this exercise taught you about the scientific method?

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7..  Also attach your Excel scatterplot with trendline, equation, and r-squared value displayed.