home *** CD-ROM | disk | FTP | other *** search
/ Exploring Creation with P…al Science (2nd Edition) / Exploring Creation with Physical Science (2nd Edition).iso / mm / mod03 / fig3_2.avi (.mp4) < prev    next >
Audio Video Interleaved Video  |  2012-12-18  |  1.6 MB  |  264x220  |  1fps  |  1 minute, 5 seconds
Transcription: We measure atmospheric pressure with an instrument called a barometer. A barometer is usually made with a reservoir of liquid, typically mercury, and an inverted evacuated tube. The term evacuated simply means there's no air in the tube. That way the liquid is free to flow up and down the tube without any resistance from air. Because atmospheric pressure is pushing down on the mercury reservoir, a column of mercury begins to rise in the evacuated tube. This will continue until the weight of the column of mercury inside the evacuated tube is equal to the force with which atmospheric pressure is ...