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Message No. 14142, Started by BeRight on 06/21/04
 Pounds Mass vs. Force In evaluating an encapsulant for a new design, I was trying to estimate the material usage.  The only relevant thing the manufacturer offers is Specific Gravity (1.35).  Using the efunda calculator, I determined that my 1.6 cubic inch cavity will use 0.078 pounds (mass) of material.  To convert to pounds of weight, I multiplied the result by 32.2 ft/sec/sec to convert to pounds force (a.k.a. "weight").  The trouble is that I'm certain this relatively small volume will not weigh 2.5 lbs!  In fact, it appears that the original result is indeed in pounds force, and not mass.  Can anyone help me out on this confusion?  Thanks.
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Follow-up Messages (20)
 Ben, thanks for your comment on this matter from Australia. When I was firs... No. 14993, Posted by sdoughty11 on 12/01/04, 19:44 PST. Things change slowly, but the advantages of SI system are so significant th... No. 14992, Posted by b1ueshift on 12/01/04, 17:05 PST. I know people who use slugs fairly often, but I personally use the other un... No. 14991, Posted by sdoughty11 on 12/01/04, 14:51 PST. 1 slug = 1G/1 lbf = (32.174 ft/s^2)/ 1 lbf 1 slug = 32.174 lbm Anyone... No. 14989, Posted by rolschwarz on 12/01/04, 14:00 PST. sdoughty11 is correct, a slug is the true unit of mass in the imperial syst... No. 14985, Posted by rorschach on 12/01/04, 09:20 PST. just KISS KEEP IT SIMPLE S.....IR No. 14981, Posted by devitg on 12/01/04, 06:06 PST. Thanks for the clarification. It is odd how some insist on sticking their ... No. 14979, Posted by beright on 12/01/04, 05:47 PST. There seems to be more heat than light generated on this problem! W = V ... No. 14973, Posted by sdoughty11 on 11/30/04, 18:48 PST. There seems to be more heat than light generated on this problem! W = V ... No. 14972, Posted by sdoughty11 on 11/30/04, 18:46 PST. often it is a huge diference between the Physic school room , and the floor... No. 14160, Posted by devitg on 06/22/04, 12:36 PST. typing witout thinking, I was.... Obviously, if water was 62.4 lbm/gallo... No. 14159, Posted by rolschwarz on 06/22/04, 12:02 PST. 1 g/cm3 gram per cubic centimeter 1×106 g/m3 gram per cubic meter ... No. 14158, Posted by devitg on 06/22/04, 09:31 PST. water density (SG=1.0): 1 kg/liter I'm sure you can find the conversion ... No. 14156, Posted by rolschwarz on 06/22/04, 06:44 PST. devitg, see this url here on efunda: http://www.efunda.com/materials/com... No. 14154, Posted by rorschach on 06/22/04, 05:36 PST. That certainly makes sense - I figured it had to be something simple like t... No. 14153, Posted by BeRight on 06/22/04, 05:13 PST. ok What's is the specific weigth for water in imperial system units ? ... No. 14152, Posted by devitg on 06/22/04, 04:27 PST. devitg, specific gravity is always unitless. it is the ratio of the density... No. 14149, Posted by rorschach on 06/21/04, 18:30 PST. 1.35 what? lb/inch3 ? ounces/foot3 ? If no units , no result No. 14147, Posted by devitg on 06/21/04, 17:05 PST. To expand on rolschwarz's answer. The mass of the volume IS the force at 1G... No. 14144, Posted by rorschach on 06/21/04, 10:57 PST. A "pound mass" is the amount of mass that weighs one pound force at 1G grav... No. 14143, Posted by rolschwarz on 06/21/04, 09:10 PST.