13 replies to this topic

[chrysalis]

ANOTHER really cool video!!

 

https://www.youtube....h?v=vwKbjFHRoTM

[TOMDEY]

Technically, one's weight lifting capability (ability to move and exert a holding force against a gravitational field) would be invariant, but the mass so-supported would vary in inverse proportion to the strength of that field.    Tom

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[TOMDEY]

Funny! --- Two other observations: 1) The guy's ability to support and accelerate his own body would vary immensely 2) he'd burn up on the sun. But this stuff remains only theoretical at this point. We should send calibrated professional astronautic weight lifters to those places to confirm the theory. At that point, it can become law.    Tom

[chrysalis]

Funny! --- Two other observations: 1) The guy's ability to support and accelerate his own body would vary immensely 2) he'd burn up on the sun. But this stuff remains only theoretical at this point. We should send calibrated professional astronautic weight lifters to those places to confirm the theory. At that point, it can become law.    Tom

Asimov would have LOVED these videos!

[Jon Isaacs]

Technically, one's weight lifting capability (ability to move and exert a holding force against a gravitational field) would be invariant, but the mass so-supported would vary in inverse proportion to the strength of that field.    Tom

 

Weight (pounds) is a force. The Newton is the unit of force in the metric system...

 

The unit of mass in the English system is the slug.. A slug is about 14.6 kg.. 

 

It is usual for people to equate kilograms to pounds but kilograms is a mass so it's not really correct.  The assumption is that the conversion is being done here on the surface of the earth.  A safe assumption for many of us..

 

Jon

Edited by Jon Isaacs, 28 August 2023 - 01:01 PM.

[TOMDEY]

 

Weight (pounds) is a force. The Newton is the unit of force in the metric system...

 

The unit of mass in the English system is the slug.. A slug is about 14.6 kg.. 

 

It is usual for people to equate kilograms to pounds but kilograms is a mass so it's not really correct.  The assumption is that the conversion is being done here on the surface of the earth.  A safe assumption for many of us..

 

Jon

Yep --- a lowly slug weighs ~32 pounds --- those English Slugs are downright frightening!    Tom

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[csa/montana]

Moved to Science! Astronomy & Space Exploration, and Others.

[yuzameh]

 

Weight (pounds) is a force. The Newton is the unit of force in the metric system...

 

The unit of mass in the English system is the slug.. A slug is about 14.6 kg.. 

 

It is usual for people to equate kilograms to pounds but kilograms is a mass so it's not really correct.  The assumption is that the conversion is being done here on the surface of the earth.  A safe assumption for many of us..

 

Jon

We've been metric, except for the regional let off of the mile and the pint (that's a proper pint, not that 16 fluid ounce thingy), for ages now, even food went from pounds to kilograms about a decade or so ago (that was the last thing to go).  I probably ought to write to our supermarkets and tell 'em to stop putting the word weight on things and change it to mass.

 

As you mentioned, weight is now measured in tons of newts, although most USA publishing Astronomy and Astrophysics versions seem to whine on about dynes when it comes to force, as USA science is still mired in cgs units it seems.  erg!!!  (prounced like an exclamation of announce).

 

I've just double checked the pedia of the wicked and the pound-foot might be the unit of force.  Man was put on the Moon using pound-feet calculations (pound-footses?).  I probably need to add a per square second there to the lbf.

 

By happenstance I've just noted that the inch variety of the slug is apparently called the 'blob' (well known for eating cinemas), but they put a blob as being a dozen times as big as a slug where my brain says it should be a dozen times smaller, as in more blobs to the slug.  The wicked pedia also goes on to state that the blob was sometimes known as the sinch, teh cgs equivalent was the glug and the mks had the mug.

 

In a touch of irony Imperial measures only survive nowadays in the first bit of the English Empire to secede, although their tons are a bit short and their pints of beer are definitely a short measure!  Especially if they give a glass exactly a USA pint large that's got a ton of froth on it.  We used to have pint glasses up North (dunno if they still do) a fair bit bigger than a pint with a mark on the side to show where the liquid should go to, the rest being for the froth.  Down here in the south though they don't like having a head on their beer and prefer it to be flat and dead looking, or they also give you some froth but use glasses exactly 1 pint big.  Thus if someone applies sideways poundfeet to you per square second the beer is easily split (that is, if they slug you, or pound you with their feet at an accelerating rate...)

[yuzameh]

Did ya hear the one about the Astronomer who went around looking for a brighter light bulb, preferably a 10²⁸ Jansky one?

 

Watt?

 

(yeah, I know, fudged a bit)

[chrysalis]

Did ya hear the one about the Astronomer who went around looking for a brighter light bulb, preferably a 10²⁸ Jansky one?

 

Watt?

 

(yeah, I know, fudged a bit)

Nah, astronomers deal in standard candles...

[gfamily]

Related is this column from Randall Munro's excellent book "What if".
https://what-if.xkcd.com/30/

NB, that he discusses Mars, but doesn't mention Ingenuity, which I'd have thought he'd have been aware of at the time.

[pretyro]

. . . 

 

I've just double checked the pedia of the wicked and the pound-foot might be the unit of force.  Man was put on the Moon using pound-feet calculations (pound-footses?).  I probably need to add a per square second there to the lbf.

 

. . . 

   I believe the term is pound force (lbf).  That is, the force that would accelerate  1 pound mass (aka lbm) at 32 ft/sec/sec.   I am of the slide-rule generation.  It is interesting to see these terms, which were ordinary back then, are now quaint.  

 

  btw, a foot-lbf is torque and a lbf-foot is energy.

[chrysalis]

   I believe the term is pound force (lbf).  That is, the force that would accelerate  1 pound mass (aka lbm) at 32 ft/sec/sec.   I am of the slide-rule generation.  It is interesting to see these terms, which were ordinary back then, are now quaint.  

 

  btw, a foot-lbf is torque and a lbf-foot is energy

Slide rule generation here too !

[lajoswinkler]

It's a quite misleading video. Being able to hold something against an attractive force (gravity, steel coil, whatever) is one thing, but to move mass is something else. Note I'm not using "up" and "down" and "lift" because these are irrelevant.

 

You would NOT be able to push 86 tonnes of steel away from Phobos' surface like that. Imagine having such steel weights on a very long pendulum here on Earth, next to a wall. Now push the steel away from the wall. It would be very similar sensation to Phobos steel lifting. You couldn't do it. Earth's gravity doesn't matter here because you're trying to push it in a perpendicular plane and vertical force is cancelled by the rope of the pendulum, just like here.