Pound Force and Pound Mass

In summary, the conversation discussed the confusion surrounding the English Engineering system and its different units of measurement, such as pounds and slugs. The concept of Gc was also mentioned, which helps convert between different units. It was noted that there are two British systems, one based on slug and the other on poundal, and it is important to stick with one throughout a calculation. Ultimately, colloquially, weight can be used interchangeably with mass or force depending on the system.
  • #1
This is the most refined concept I could make by reading wikipedia. Our thermodynamics' teacher today introduced us to the 'real' English Engineering system.

My confusion was that like we know if we want to find the weight of a 51 kg person we would simply multiply it with 10(approx) and get 510 N.If we have 51 lbm and want to convert it into lbf then we can't simply multiply it with 32.2(approx) and get the answer but we will also have to take that 'g subscript c' into account which is also 32.2 and so these two 32.2s cancel out and we get 51lbf.

Am I right?
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  • #2
You are correct. Just remember in the English system, the direct correlation to the kg is NOT the Lbm. It is the slug. In that case you don't have to worry about Gc.

Take a look here and notice the table at the top of the article.
http://en.wikipedia.org/wiki/Slug_(mass [Broken])
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  • #3
Thanks a lot.
  • #4
There are actually two "British systems".
1. A body with a mass of 1 slug weighs 32 pounds.
2. A body with a mass of 1 pound weighs 32 poundals.
Of course, you have to stick with one or the other throughout a calculation.
So "pound" can mean either "mass" or "force", depending on the system.
One of these systems (I think the poundal) was called the "engineering" system.
In any event, colloquially, if an American "weighs" 220 pounds, his European twin
"weighs" 100 kilo, even if some terms are used incorrectly.
  • #5
Got it. Thanks

What is a pound force?

Pound force is a unit of measurement for force, commonly used in the United States and United Kingdom. It is defined as the force required to accelerate a mass of one pound at a rate of one foot per second squared.

What is a pound mass?

Pound mass is a unit of measurement for mass, commonly used in the United States and United Kingdom. It is defined as the mass of one pound avoirdupois, which is equal to 0.45359237 kilograms.

What is the difference between pound force and pound mass?

The main difference between pound force and pound mass is that they are used to measure different physical quantities. Pound force measures the force applied to an object, while pound mass measures the amount of matter in an object.

Can pound force and pound mass be converted to each other?

Yes, pound force and pound mass can be converted to each other using the gravitational constant, which is approximately 32.174 feet per second squared. The conversion formula is: 1 pound force = 32.174 pound mass.

Why are pound force and pound mass still commonly used in the US and UK?

Pound force and pound mass are still commonly used in the US and UK because they are deeply ingrained in their respective measurement systems. These units have been used for centuries and are deeply rooted in their cultures, making it difficult to switch to a different system of measurement.