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| My general tinkerings – Part 2 | ||
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Description: This is a past physics project (Part A-Level and part personal interest), where the aim was to use Boyles' law to determine atmospheric air pressure. Basically, if you halve the volume of a gas, the pressure will double, but only on the absolute pressure scale. Do some maths jiggery-pokery on the volume ratio and the (Relative) pressure applied and you can work back to find the atmospheric (Absolute) pressure. The two U-Tubes are filled with water, the left one is capped at the top, and the air contained within the pipe is compressed above the liquid's surface. The right tube serves as a manometer to measure the pressure applied as accurately as possible. (A correction is needed to the pressure measured as the movement of water in the left U-Tube creates it’s own manometer effect, thereby partially cancelling out some of the applied pressure). Although the deduced atmospheric pressures were slightly out from local barometer readings, they weren’t that far out by experimental standards (E.g. On one day the atmospheric pressure was ~1023mBar, and the experiment gave ~985mBar which is only about 4% out) Picture Stats: Views: 1287 Filesize: 273.46kB Height: 768 Width: 1024 Posted by: Hodgkinson at June 01, 2008, 02:23:43 PM Image Linking Codes
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| weirdami Posts:3776 | September 12, 2008, 11:38:33 AM manomoter sounds like something they used in the 70's back when it rained men. or, perhaps, it's good for measuring the general man-ness of an individual... like a stud finder, only less beepy and more liquidy. :idea: |
| Hodgkinson Posts:1080 | June 02, 2008, 09:36:54 AM :-D That's why I preferred to use the manometer with lower pressures as opposed to the dial gauge at the top (Which is only there if I needed to use this setup for something involving higher pressures). Besides, with lower pressures, there's less chance of any of the bungs flying out from the top of the tubes, and, errr, well, you can guess what might happen to the MDF on which it’s mounted and the 4 computers + CRT monitor just to the right hand side... (I did have a slow leak once when I tried to clamp the bungs into place - The pipe wasn't even and, under pressure the water gradually went higher and higher up the tube until it started dripping out the top - Oh ... etc...What with the non-return valve on the pump fitting...) |
| Damion Posts:3511 
| June 01, 2008, 08:54:10 PM Cool project! :pint: Reminds me of the "homebrew" manometer l I made to sync the carbs on my motorcycle... (a u-tube on a ruler, filled with a little ATF). Cost less than $3 and is far more accurate than most dial gauges.  |