| ▲ | brudgers 8 months ago |
| Or 7.662481e-14 parsec/sec, 1467.9126 Newtons, and 4.4041166e-16 light years. Because space. |
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| ▲ | 7734128 7 months ago | parent | next [-] |
| You can't turn mass into force, especially not in space. |
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| ▲ | brudgers 7 months ago | parent [-] | | For the metrically challenged, pounds are a unit of force not mass. | | |
| ▲ | littlestymaar 7 months ago | parent [-] | | Wikipedia disagrees with you[1], and if pounds were a unit of weight that'd be very unpractical from a legal PoV to have things being labeled in pounds since the same object have a different weight in Puerto Rico (close to the Equator) and Fairbanks (close to the North Pole). [1]: https://en.wikipedia.org/wiki/Pound_(mass) | | |
| ▲ | delta_p_delta_x 7 months ago | parent | next [-] | | To be very pedantic, the pound is a unit of both force and mass, and it's because the unit evolved before the Newtonian understanding of weight versus mass. That's why there exists the pound-mass, and the pound-force. Of course, in SI this is very straightforward: the unit of mass is the kilogram and the unit of force is the newton, which is the force acting on a mass of one kilogram experiencing an acceleration of one metre per second per second in an inertial frame of reference. | |
| ▲ | brudgers 7 months ago | parent | prev | next [-] | | Your comment is ambiguated. https://en.wikipedia.org/wiki/Pound | |
| ▲ | two_handfuls 7 months ago | parent | prev | next [-] | | I distinctly remember reading how I would weigh a different amount on the moon. This only makes sense if the pound is a unit of force. | | |
| ▲ | stouset 7 months ago | parent [-] | | You would weigh a different amount on the moon, but that is completely independent of how we label our units of measurement. The pound a unit of force. It is also a unit of mass. Both units share the same name. | | |
| ▲ | two_handfuls 7 months ago | parent [-] | | It's not independent because if I'm 80kg here, I'm still 80kg on the moon. Because gravity does not affect mass. If I weigh 160lb on earth I'm told that I would weigh 26lb on the moon. That makes sense if lb measures force because gravity affects force. In short, this commonly shared "fact" is consistent with pounds being a unit of force, not of mass. Or, I suppose, of lb at least sometimes being a unit of force. | | |
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| ▲ | M3L0NM4N 7 months ago | parent | prev [-] | | I think it's used as both. Foot-pounds is used as a unit of work, so it's a force in that context. |
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| ▲ | beAbU 7 months ago | parent | prev | next [-] |
| In case you didn't understand the other reply, you can't use newtons in this context. Kilograms is perfectly fine here. The thrust of the engine can (and should) be measured in newtons though. Also, 4 decimal points of precision is completely overkill. Maybe one decimal point at most would be more than enough, but most wouldn't even bother with that. |
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| ▲ | foxglacier 7 months ago | parent | next [-] | | The problem is the 8 significant figures, not 4 decimal places - 0.3300 kip and 1467.9126 N both have 4 decimal places but one is much worse than the other. Even if 330 lb was exact, all those digits in 1467.9126 N aren't even correct. It should be 1467.9131 N using standard gravity. It looks like brudgers used 1 lbf = 4.44822 N which is what Google says but is only rounded to 6 s.f. so can't be used to generate an 8 s.f result. | | | |
| ▲ | nordsieck 7 months ago | parent | prev | next [-] | | > The thrust of the engine can (and should) be measured in newtons though. It's very common to measure engine thrust in ton-force because it makes it easy to compare the thrust to the weight of the rocket, which is a critical metric. | |
| ▲ | brudgers 7 months ago | parent | prev [-] | | The force of a rocket engine can be measured in pounds. And pressure in PSI and torque in foot-lbs because pounds are a unit of weight (i.e. force) not mass. |
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| ▲ | 7 months ago | parent | prev [-] |
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