This is not a pitting of dopers, as they tend to be kinder but the unit of measure nazis are just as frustrating as the prescriptive grammar nazis in general.
This is absolutely pervasive throughout both the general public and non-physics scientists where they obsess about the difference between weight and mass, typically while referencing pounds vs kilograms or ounces vs grams.
First, of all the pound has been defined based on the kilogram for over 50 years, and so unless someone is using pounds force or lbf they are the EXACT same measurement with just a change in the scale. <pdf>
Second, the kilogram is a measure of “inertial mass”, or the inertial resistance to acceleration. Weight, or a measure gravitational force experienced by the body when in a reference gravitational field is functionally the same measurement under the standard model. Einstein’s equivalence principle states that within sufficiently small regions of space-time, it is impossible to distinguish between a uniform acceleration and a uniform gravitational field.
But you say…but a kilogram is still a kilogram on Jupiter but a pound is not! This is only true if you set arbitrary limits to the accuracy and is not true out of the newtonian model which as we know, while useful, is not true!! Due to general relativity the pseudo-force(1) we call gravity is known to be an acceleration force in space time. This means that the total energy state will change when an object is subject to a change in gravitational force which will change it’s mass, just as the mass of a running clock is higher than a stopped clock, it may be a small change but it is there. The E=MC^2 that the same unit of measure nazis wear on teeshirts and coffee mugs makes this true.
So get over yourselves, mass and weight are useful constructs that are both only valid in within a reference frame, quit confusing the public and your peers with false absolutes which are as outdated as references to phlogiston.
*(1) Don’t get me started about how the pseudo-force of gravity is universally OK but people will kvetch if you mention the also useful pseudo-force called centrifugal force.
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