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03-26-2015, 02:29 PM - 2 Likes   #391
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C'mon guys; any good engineer knows the prime universal of physics, or "the law of movement".


"If it doesn't move and it should = WD40. If it moves and it shouldn't = DUCT TAPE."

03-26-2015, 02:36 PM   #392
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In my (long ago) school days, stones, pounds and ounces were the units of weight. Grams and kilograms were units of mass. Ah, life was simpler then.
03-26-2015, 02:41 PM   #393
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QuoteOriginally posted by tuco Quote
Yes, it matters. See this book? It is full pre-solved beam and other equations good for both imperial and metric units. If you stick in "kilograms" for weight or force in any of these equations, you will get the WRONG answer both in units and magnitude.

What school of engineering did you graduate from that taught you a different metric system were weight and mass have both the same units and value? 1 kilogram of mass weighs 9.81 Newtons. Those don't look like the same numbers to me.
How much does the book weigh?
03-26-2015, 02:42 PM   #394
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QuoteOriginally posted by D1N0 Quote
How much does the book weigh?
It weights 5 watt. If we are going to make up any unit for weight, here is mine.

03-26-2015, 02:45 PM   #395
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QuoteOriginally posted by rburgoss Quote

"If it doesn't move and it should = WD40. If it moves and it shouldn't = DUCT TAPE."
hehe, nice to read that on the other end of the world the same rules apply :-D
03-26-2015, 02:49 PM   #396
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QuoteOriginally posted by tuco Quote
It weights 5 watt. If we are going to make up any unit for weight, here is mine.
you can't weigh energy
03-26-2015, 02:52 PM   #397
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QuoteOriginally posted by D1N0 Quote
you can't weigh energy
E=MC2 means that mass can be converted into energy and energy can be converted to mass.


.... and .... This also is not true.... 74,400,000 Google pages on this very debate ! Have fun !
03-26-2015, 03:00 PM - 1 Like   #398
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QuoteOriginally posted by carpents Quote
I worked for a Norwegian company many years ago. During the Lillehammer Olympics they set up TVs in all the offices to watch.

When the Norwegian was preparing for the ski jump, the American announcer called him the 'Swedish ski jumper'. What howling ensued!
Last ski jumper I remember (when I watching the winter Olympics) was Matti Nykänen. Only he was Finnish.
That is how I remember him every time I wear a skiing jumper (pun intended).




Last edited by Uluru; 03-26-2015 at 03:06 PM.
03-26-2015, 04:04 PM   #399
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QuoteOriginally posted by infoomatic Quote
hehe, nice to read that on the other end of the world the same rules apply :-D
That is exactly why it is called "universal". Because it has the same validity in every single language, creed, political affiliation and sex preference known to humanity.
03-26-2015, 04:25 PM   #400
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QuoteOriginally posted by tuco Quote
Clearly, in Newtonian Mechanics, Weight = (mass)*(gravity) and the product of those two things does not have the units of "kilograms" (or the same value).
Sure. It's just a convention.

Engineering in metric countries seems to flourish regardless.
03-26-2015, 05:38 PM - 1 Like   #401
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QuoteOriginally posted by tuco Quote
That's good to hear but yet I see so much technical data from companies outside the USA that gives things such as cable tension limits and weight of things in kilograms.
Are you sure that you saw the weight of something being specified rather than its mass?

Since gravitational mass and inertia mass are equivalent, one can measure the mass of something by weighing it (and converting considering the gravitational field).

A scale for body weight on earth is not intended to report the force that your body produces in earth's gravitational field, but the mass of your body. Hence the unit used is "kg" not "N".

I suspect that in all your observations the unit "kg" is correctly used to express the mass of something.

The imprecision is only in everday language where people do not consider other gravitational fields (e.g., that on the moon) and therefore do not distinguish between weight and mass. That unawareness of the difference between these concepts probably exists just as much in countries that do not use metric systems, if only through lay people pretty much never using the unit for mass.

QuoteOriginally posted by tuco Quote
So what units does the typical layman say in your area when they are talking about a moment (torque). Kilogram-meter? If they say newton-meter than I'd really be blow away by the inconsistency.
They use Newton-meter, of course, since only a force is involved.

Kilogram-meter, would only make sense if the force were created by a mass, which is typically not the case.

Last edited by Class A; 03-26-2015 at 05:50 PM.
03-26-2015, 06:08 PM   #402
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Tuco, hear hear, some strong words from someone from a country refusing to solve/avoid some problems because of the persistence of the use of antiquated units... Someone remembering the Mars Climate Orbiter? Or, to somehow come back to a photography related topic, some of the problems with the Hubble Space Telescope, due to "conversion problems". Well... ;-)
03-26-2015, 06:21 PM   #403
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QuoteOriginally posted by Class A Quote

They use Newton-meter, of course, since only a force is involved.
Of course, for a while there, Class A, the BBC TV show Top Gear was saying 'torques' instead of Newton-meters when referring to engine performance.

That's right, to dumb things down for the audiences.

Best not to argue with Jeremy Clarkson, though - you might get punched in the face!
03-26-2015, 07:06 PM   #404
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QuoteOriginally posted by clackers Quote
Of course, for a while there, Class A, the BBC TV show Top Gear was saying 'torques' instead of Newton-meters when referring to engine performance.

That's right, to dumb things down for the audiences.

Best not to argue with Jeremy Clarkson, though - you might get punched in the face!
Oooo weeeee.............Top Gear Slam!!!
03-26-2015, 07:28 PM   #405
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QuoteOriginally posted by Stavri Quote
Oooo weeeee.............Top Gear Slam!!!
I think we might find a new show coming out of ITV next year ...
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