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Tufts OpenCourseware
Author: Fulcrum Institute Development Team

Coffee and Cream Investigation Sheet

A Fair Comparison

Try to create identical conditions for each test so that you can understand the effect of changing just one variable: the time when you add the cream.

  • Set up your temperature probes and Logger Lite to prepare to collect data for about 100 minutes. See Tips for Using Vernier Temperature Probes.
  • Start with both probes at the same temperature. Record room temperature.
  • Set up the probes so that the tip of the probe is suspended in the middle of each of 2 identical cups. (We did this by suspending the probes from the thermometer clamps on the support stand and rod.) Now you are ready to measure the coffee temperature in each cup.
  • Make a pot of hot (~80°C) coffee (remember, hot water can stand in for the coffee). Pour exactly the same measured amount (80 ml) into each cup.
  • Begin to collect temperature data.
  • Immediately add an accurately measured amount (20 ml) of cold (~15°C) cream to one cup and return the rest of the cream to the fridge.
  • After 2 minutes, add 20 ml of cream from the fridge to the second cup.
  • Continue to monitor and record the temperatures until both cups reach room temperature. (You can just leave the investigation to run on its own if you prefer, once you're sure your computer is generating a graph.)