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$Lb_m$ is not the base unit. The Slug is the base unit. $32.2\ lb_m = 1\ slug$ To convert $1\ lb_m$ to $lb_f$: $1\ lb_m * \frac{1\ slug}{32.2\ lb_m} * 32.2 \frac{ft}{s^2} = 1\ lb_f$ Therefore $1\ lb_m$ will yield $1\ lb_f$ on Earth at STP. This video does an excellent job of explaining it.


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The textbook is incomplete. Newton's Law is usually written $F=ma$. The SI unit of mass is the $kg$ and that of force is the $N$. One of the advantages of SI is that it clarifies the distinction between mass and force (especially weight). In the old British Imperial system there are several options: we can measure mass in pounds_mass $lbm$; the ...


4

1 pound mass is that mass that weighs one pound in 1 g gravity. For most practical cases, a pound mass and a pound weight define the same amount of stuff on the surface of the earth. To define a pound mass we rearrange Newton's law of F = mA to m = F/A then plug in the particulars to get pound mass: 1 pound mass = (1 pound force)/(32.174 ft/s²)


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Take all this with a grain of salt. I work in Germany as an engineer and don't have any special license sides my degree, but I'm employed and your situation may be different. Generally, engineer is a free profession in Germany. This means, if you are an engineer (have an engineering degree from a university or a university of applied science), you can ...


4

There seems to be some confusion here. In the English (or American) system the "official" measure of mass is the slug. Turns out that 32.2 lbm = 1 slug. So to plug into the equation F=MA you can use M in slugs, A in ft/sec and F in lbf. And, as someone said, at "standard" gravity 1 lbm exerts 1 lbf on its support (its weight). If you are going to do any ...


4

I wrote this paper in response to a declaration made by Dynamics Professor that "there is no difference between a lbm and lbf." The discussions from the students that followed exposed a huge concept error that seems to stem from the misuse of the above statement. It has some comedic relief, so it makes it more bearable ;) Enjoy! The lbm-lbf Relationship: ...


4

lbf has two definitions and a friend called Poundal (1) EE System The force required to accelerate 1 lbm 32.174049 ft/s^2 (i.e., acceleration due to gravity) However, the problem with this is that it MUST retain 32.174049 in its units! Which is not ideal, Consider F = ma, which means ma will always have to be divided by 32.174049 making this equation F =(...


3

They can't even write English on their certificate. ... training of good stand, and is in accord with American and European standers... That's an obvious typo. Of course it should say ... training of good sit, and is in accord with American and European sitters... Is it worth paying $300 for a joke certificate? That depends on the buyer's sense ...


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50μm → 0.002" or 2 thou or 2 mils? I've seen both 0.002" and 2 mils. On a drawing it would always be 0.002". In a specification document it could be either. I've never seen 2 thou written in a formal specification (but I have heard people say it in the shop). But that might just be my experience. There could be variation from industry to industry. Is ...


1

lbm and lbf are not the same -- they are only of the same value in one situation, when dealing with gravity at sea level... examine a situation without gravity, the force produced by a jet of water. density of water: 62.4 lbm/ft3 area of nozzle: 0.06 ft2 velocity: 10 ft/s volume flow = area * vel = 0.6 ft3/s F = dwater * volume flow * vel = 374.4 lbm ft/s2 ...


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I will try to make it as simple as possible and will provide an example: -First of all ignore the word slug... I know it is the standard unit for mass and so is lbm. you will see lbm used in your text and in real life 99% of the time. Once you understand this concept well you can go on to familiarize yourself to using slugs. -Think of newton as the force ...


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Absolutely, yes you can. In fact, the mass of a slug is derived from the acceleration due to gravity.


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