4 ms·

You missed the point of your respondent. Weight and mass are different things, mass in kilograms usually translates through Earth's gravity into a 2.2 to 1 rela

You missed the point of your respondent. Weight and mass are different things, mass in kilograms usually translates through Earth's gravity into a 2.2 to 1 relationship with weight in pounds. Because 1.8 * 2.2 ~= 4 it's unambiguously referring to Earth weight, on Mars the ratio is 0.83 pounds per 1 kg. The helicopter would weigh 1.5 pounds if you took a load cell calibrated in pounds and measured it on Mars, but it would still have a mass of 1.8 kg. There's no such thing as "Earth mass" and "Mars mass", they're the same. Calling this helicopter a 1.5 pound Mars weight helicopter seems confusing.

drran 7y ago
Pound and kilogram are same thing at different scales. The sooner US will abandon Imperial scale, the better.
- s5reahare5hba 7y ago
  Gets complicated because rocket thrust is measured in Newtons but often converted to Pounds, 1 Newton = 0.22 Pounds of thrust
- p_l 7y ago
  Welcome to the confusing short hands of pound-force and kg-force! It's huge part of why Newtons were used in SI instead of gram-force in CGS. Still persists in thrust calculations, especially as metric ton-force, due to ease of calculating TWR and related.
perl4ever 7y ago
I didn't miss the point; the point was "X is not ambiguous if you assume Y to resolve the ambiguity". If you assume that the writer considered kg to only mean mass you can infer that they were talking about earth weight in lbs. But I don't think one can reasonably assume that, when they wrote weight and didn't specify where, when Mars weight would be more relevant. If someone isn't being clear and precise, then you can't resolve meaning by assuming clarity and precision. Interpretation doesn't govern reality. This is reminding me very strongly of the perennial discussions of undefined behavior handling by compilers.
- LeifCarrotson 7y ago
  Oh, you think they took a 4 lbs Martian weight and erroneously divided by 2.2 to get kg? The 'assumption' that kilograms mean mass is a fact, not just personal preference, though I can see how a journalist might miss the distinction and make the error if they only had pounds and their editor said "all units must be reported in metric and imperial". Regarding compilers, resolving this would be like checking that a size_t result (guaranteed to be unsigned) was greater than zero. Sure, it's nice when writers make clear their basic assumptions if they expect their readers to have little knowledge of the subject. We're in the unique position of expecting a writer to have little knowledge, expecting them to be self-aware of that, and expecting them to recognize there's a potential distinction to be drawn between Earth weight, Mars weight, and mass.

drran 7y ago

Pound and kilogram are same thing at different scales. The sooner US will abandon Imperial scale, the better.

s5reahare5hba 7y ago
Gets complicated because rocket thrust is measured in Newtons but often converted to Pounds, 1 Newton = 0.22 Pounds of thrust
p_l 7y ago
Welcome to the confusing short hands of pound-force and kg-force! It's huge part of why Newtons were used in SI instead of gram-force in CGS. Still persists in thrust calculations, especially as metric ton-force, due to ease of calculating TWR and related.

perl4ever 7y ago

I didn't miss the point; the point was "X is not ambiguous if you assume Y to resolve the ambiguity". If you assume that the writer considered kg to only mean mass you can infer that they were talking about earth weight in lbs. But I don't think one can reasonably assume that, when they wrote weight and didn't specify where, when Mars weight would be more relevant. If someone isn't being clear and precise, then you can't resolve meaning by assuming clarity and precision. Interpretation doesn't govern reality. This is reminding me very strongly of the perennial discussions of undefined behavior handling by compilers.

LeifCarrotson 7y ago
Oh, you think they took a 4 lbs Martian weight and erroneously divided by 2.2 to get kg? The 'assumption' that kilograms mean mass is a fact, not just personal preference, though I can see how a journalist might miss the distinction and make the error if they only had pounds and their editor said "all units must be reported in metric and imperial". Regarding compilers, resolving this would be like checking that a size_t result (guaranteed to be unsigned) was greater than zero. Sure, it's nice when writers make clear their basic assumptions if they expect their readers to have little knowledge of the subject. We're in the unique position of expecting a writer to have little knowledge, expecting them to be self-aware of that, and expecting them to recognize there's a potential distinction to be drawn between Earth weight, Mars weight, and mass.