Cooling Water and Exponential Funtions

Essay by pauldud85High School, 11th gradeA+, January 2003

download word file, 4 pages 4.1

The Water Cooling Experiment

During this lab we measured, using our CBL's and graphing calculators, the change in temperature of a glass of boiling water left to cool in a room. The purpose of the lab is to see how exponential functions can be applied to real-life applications. During the experiment I'm expecting for the water temperature to decrease as soon as the water is taken of off the heating device. If the water is left in the room long enough, the temperature will be able to reach room temperature, no less.

Using the calculator, CBL, and temperature probe, the room temperature was taken to find out the lowest temperature the water could cool to (the asymptote). To get the most accurate room temperature reading, I had to keep the probe extremely still because movement could cool off the probe and give a false reading. Also by shortening the intervals in which the CBL took the readings allowed for accurate results.

A glass of water was then brought up to boiling temperature. After the water started boiling, a temperature probe (connected to the CBL) was left in the water as the calculator and CBL took temperature readings. I let the probe sit in the water for a few seconds before starting the temperature readings to allow the probe to heat up to the same temperature of the water. This prevented the results from showing an increase and then decrease in temperature. The readings were taken every 60 seconds for 36 minutes.

The data, as stated before, was expected to resemble an exponential decay function. The graph reinforced this hypothesis by showing an original steep decrease in temperature, and then slowing down as it neared the asymptote (room temperature) at 22.11 degrees Celcius (see figure 1). This data...