Mixing the bath water just right
When you mix water at two temperatures to make a bath that's just right for bathing, one is usually too hot and the other is too cold. How much of each is needed? In this trial you need to have two samples of water at different temperatures, but in equal amounts. In two Stryofoam cups, measure out small equal volumes of any two of the following, using the film canister as a standard measure:
water cooled with ice
cold tap water
room temperature water
warm tap water
Connect the Temperature probe with your handheld. Refer to Technical Hints to see how to connect the Temperature probe. The sensitive part is just the very tip, where two wires are welded together.
What will happen when you touch the end of the probe and then let go? What happens when you put the probe in water? Record your thoughts in Notes on your handheld computer.
Start the software and observe the temperature versus time graph as you test your two choices of water. Stop the software. Be sure the two samples are at least 10 degrees Celsius different from each other. What are the two temperatures?
Before mixing the two samples of water together, predict the final temperature.
Make the temperature measurements one after another with the graph running. You will then have all of your data on one graph, and you can analyze it.
Restart the graph and retest the temperature of each sample of water.
Pour one water sample into a third Styrofoam cup. Quickly place the Temperature probe in the water. Slowly add the other water sample to the third cup. Observe the graph.
Stop recording when you think the temperature has come to a relatively stable temperature (equilibrium). Save your data to the handheld.
