http://engineerography.com/2009/03/what-the-hecks-the-difference-between-pound-force-and-pound-mass/ Studying and writing about everyday engineering, since 2009. Wed, 04 Apr 2012 14:52:04 +0000 hourly 1 http://wordpress.org/?v=3.1 http://engineerography.com/2009/03/what-the-hecks-the-difference-between-pound-force-and-pound-mass/#comment-1225 Izhaar Wed, 04 Apr 2012 14:52:04 +0000 http://engineerography.com/?p=360#comment-1225 Hi, This was very useful. I was scratching my head to find the difference between the two. Thanks lot. :) Hi, This was very useful. I was scratching my head to find the difference between the two. Thanks lot.

]]> http://engineerography.com/2009/03/what-the-hecks-the-difference-between-pound-force-and-pound-mass/#comment-1224 Robin Hewitt Tue, 20 Mar 2012 15:53:30 +0000 http://engineerography.com/?p=360#comment-1224 But is the Slug defined at the equator or at the Royal Observatory, Greenwich? Gravity varies by latitude and mass concentration so it makes a difference. But is the Slug defined at the equator or at the Royal Observatory, Greenwich? Gravity varies by latitude and mass concentration so it makes a difference.

]]> http://engineerography.com/2009/03/what-the-hecks-the-difference-between-pound-force-and-pound-mass/#comment-1210 Taylor Wed, 09 Nov 2011 18:34:39 +0000 http://engineerography.com/?p=360#comment-1210 Thank you for posting this! clears up soooo much confusion... My teacher who's a working engineer explained this to me wrong and said anytime something is talking about lbm, I need to multiply it by 32.174 ft/s^2. My answers were not matching up with the textbook, he had me believing the text book was wrong! It would help if my textbook explained the english system in this way... Up until this point I was like your friends, converting english units into metric units... I now have a much more clear picture of how these work. Thank you Tom for the equation F = mg/gc as this is a useful way to think about it. my question is now, When would you simply multiply lbm by 32.174 ft/s^2 to end up with an accurate lbf? Thanks yall! Thank you for posting this! clears up soooo much confusion… My teacher who’s a working engineer explained this to me wrong and said anytime something is talking about lbm, I need to multiply it by 32.174 ft/s^2. My answers were not matching up with the textbook, he had me believing the text book was wrong! It would help if my textbook explained the english system in this way… Up until this point I was like your friends, converting english units into metric units… I now have a much more clear picture of how these work. Thank you Tom for the equation F = mg/gc as this is a useful way to think about it. my question is now, When would you simply multiply lbm by 32.174 ft/s^2 to end up with an accurate lbf? Thanks yall!

]]> http://engineerography.com/2009/03/what-the-hecks-the-difference-between-pound-force-and-pound-mass/#comment-1208 Nima Sun, 16 Oct 2011 04:23:36 +0000 http://engineerography.com/?p=360#comment-1208 awesomeeeeeeeeee.Thanks! awesomeeeeeeeeee.Thanks!

]]> http://engineerography.com/2009/03/what-the-hecks-the-difference-between-pound-force-and-pound-mass/#comment-1198 Tom Wed, 02 Feb 2011 20:28:51 +0000 http://engineerography.com/?p=360#comment-1198 Ignore my last comment/question. I studied this some more and this website actually has the correct information, it's the ehow.com website that's wrong. Apparently you cannot simply use Newton's 2nd law F=ma as simply lbf=lbm*g as the ehow.com site does. I now understand there's a proportionality constant "g sub c" or gc which is 32.17 lbm ft/lbf s^2 which must be used. So Newton's 2nd law is written F=ma/gc when using imperial (English) units. Thus F=mg/gc, and g and gc will cancel each other out. If you simply use F=ma as lbf=lbm * g then there is no way that lbf = lbm, but using F=ma/gc allows lbf = lbm when g=32.17. Now I comprehend. And the ehow.com website is the incorrect one. Ignore my last comment/question. I studied this some more and this website actually has the correct information, it’s the ehow.com website that’s wrong. Apparently you cannot simply use Newton’s 2nd law F=ma as simply lbf=lbm*g as the ehow.com site does. I now understand there’s a proportionality constant “g sub c” or gc which is 32.17 lbm ft/lbf s^2 which must be used. So Newton’s 2nd law is written F=ma/gc when using imperial (English) units. Thus F=mg/gc, and g and gc will cancel each other out. If you simply use F=ma as lbf=lbm * g then there is no way that lbf = lbm, but using F=ma/gc allows lbf = lbm when g=32.17. Now I comprehend. And the ehow.com website is the incorrect one.

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