A Barometer For The 7th Grade Science Fair
Torricelli and the Barometer Torricelli was an Italian mathematician and scientist who lived during the fifteenth century. He was a contemporary of Galileo. He is best known for his invention of the mercury barometer and his explanation of how it works. In Torricelli's day there people who believed that the air which surrounds us was weightless. Torricelli thought otherwise. Through the use of a mercury-filled glass tube around a meter in height, with one end closed and the other submerged in a bath of mercury, Torricelli showed that it was the atmosphere pressing down on the mercury that kept the column of mercury in place. This meant that the air all around us has weight and exerts pressure. He also noted how the level of the mercury changed every day and stated that this was due to conditions in the atmosphere. The mercury barometer proved a convenient method for predicting changes in atmospheric pressure and weather conditions. This meant that people could be better prepared for weather changes. Make Your Own Barometer For your 7th grade science fair project, you can follow in Torricelli's footsteps and make your own barometer. Use your barometer afterwards to observe how weather and air pressure are related. To make your own barometer, you need a wide-mouthed jar, a balloon, a drinking straw, tape, scissors, a pin, a strip of cardboard, and a marker. To start with, you should cut the balloon and stretch it over the mouth of the jar so that it is as tight as a drum. Lay one end of the straw on the balloon and tape it into place horizontally. The longer your straw is, the more obvious the changes in pressure will be because the other end of the straw will move farther. On the free end of the straw, tape a pin horizontally. This will serve as your pointer. To make a scale, stand a strip of cardboard vertically behind the pin. Mark the position of the pin with a horizontal line using your marker. This will be your center line. Then make two more lines, one above the first line and one below, at equal distances from the center. Place your barometer somewhere outside where you can conveniently read it. Record the position of the needle when there is good weather and when the weather is bad. Note what kind of weather happens after the pin rises and what kind of weather follows after the pin gives a lower reading.
|