Just what exactly is a G?

[Fritz_Brown]

Oops. That should be north/south (the tick marks on the longitude lines), not east/west.
I always had to stop and think which way was which, and yesterday I didn't.
What I get for being a smart-aleck.

 

[BetterThanLife]

Originally posted by Fritz88:
Oops. That should be north/south (the tick marks on the longitude lines), not east/west.
I always had to stop and think which way was which, and yesterday I didn't.
What I get for being a smart-aleck.

It should also be at sealevel, without a wind.

remember Airspeed is traditionally measured in Knots as well.

 

[Fritz_Brown]

Actually, airspeed is airspeed, and ground speed is ground speed. That's where wind comes in. Tracking yourself over a map/chart would be groundspeed. Reading your "air velocity indicator" tells how fast your cheeks would be flapping if you were on the outside.

Altitude effect is negligible for an aircraft (when doing real world stuff) because your height is miniscule compared to the diameter of the earth.

Satellites, and all, is TOTALLY different. I seem to remember doing orbital calculations in km/sec, etc. Metric is better for c and G.

I think its best, though, to change from gaming session to gaming session. It's a way of keeping a flavor of Star Trek (Original Series) in the game.

 

[Straybow]

Consistency of units in SI? What about kms vs cgs?

I'd have to say that 6 feet is medium verging on small. Everything depends on perspective.

Yes, although for somewhat opposite reasons for me. I was always small in school, 'cause I was almost a year younger than my classmates. When I reached full height in high school I was still small. Then I go to college and find out I'm average height.

In high school all my friends were tall, even the various orientals were taller than me except for one guy. It took me years to retrain my thinking.

 

[BetterThanLife]

Originally posted by Fritz88:
Actually, airspeed is airspeed, and ground speed is ground speed. That's where wind comes in. Tracking yourself over a map/chart would be groundspeed. Reading your "air velocity indicator" tells how fast your cheeks would be flapping if you were on the outside.

Altitude effect is negligible for an aircraft (when doing real world stuff) because your height is miniscule compared to the diameter of the earth.

Satellites, and all, is TOTALLY different. I seem to remember doing orbital calculations in km/sec, etc. Metric is better for c and G.

I think its best, though, to change from gaming session to gaming session. It's a way of keeping a flavor of Star Trek (Original Series) in the game.

How is metric better for things like gravity? 9.81 meters per second squared vs. 32.2 feet per second squared? (And that is only 3 digits for both.) If you want things to be useful for G then define a unit of measure as 1/12th or 1/10th the height an object falls from in a vacuum at sealevel to strike the ground in 1 second. All calculations in both Imperial units and SI units for the average person are approximations for most applications anyway. The speed of sound at sea level at standard atmosphere and pressure is approximately 300m/s, or approximately 1100ft/s. Actual numbers are 1116 Ft./Sec or 340.2 M/Sec. Light travels 299,792,458m/s, or 983,571,056ft/s. What is the difference between the two measurement systems?

When you are talking about light years, any rounding at all will cause you to miss the target by quite a bit over interstellar distances. If you use 3x10^8m/s as the speed of light, and a nice calculation on relative movement between here and Proxima (4.36 light years+/-) firing a laser between here and there you not only wouldn't hit the star you probably wouldn't even have the beam pass through the system within the Oort cloud.

Both systems are arbitrary, and equally accurate (Or should I say equally inaccurate?). The only advantage that SI has over Imperial is that more people on Earth use it. And then, when it comes to SI units, most people use the weight/force/mass part of it wrong! I agree we should, as a people, use one system but stating one is superior to the other based on anything besides familiarity is ludicris.

 

[Straybow]

Danged Frogs!

 

[womble]

Bhoins:
"...The only advantage that SI has over Imperial is that more people on Earth use it...."

If the advantages described in this thread don't change your mind, then nothing will.

The biggest advantage of the SI system is its scalability. kg=10^3 g; l=1000ml. There's a unit for any scale that works consistently using the same multiplier for scales of different orders. Imperial units use a mix of multipliers: lbs->oz is 16 (in British), lbs to stone is 14, stone to hundredweight is 8 stone; hundredweight to ton is 20, lbs to ton is 2240, yards to miles is 1760, feet to inches is 12 and so on. And these are basic dimensions of units. When you want to measure derived quantities (Energy, impulse, charge, acceleration), they multiply together into a mess that needs a myriad different conversion ratios depending on which basic unit you chose: feet/lb/s based systems are not easily convertible into inch/oz/s, whereas kms into cgs is easy. I have never heard torque measured in 'millifootpounds', and how that would convert into... inchounces (/12/16) is hardly an easy sum.

Of course the measures are arbitrary. So are the constants they are used to measure; no one system will ever produce whole numbers for Planck's constant, the distance a Roman soldier covers in a thousand double-paces, the distance sound travels in one time unit and the distance light travels in one orbit of this planet around its primary. It's the way the units work together which makes a system which works. It's not about accuracy it's about a rational, consistent system, which Imperial patently is not, since it has grown from and diverged across ages of time and culture.

 

[PBI]

Amen, womble

 

[rvatsaas]

When I run, I have a pretty good feel for how far a mile is.

When I cross country ski, I can also estimate well, except I will think in kilometers, the traditional unit for measuring ski trails.

When I am carrying a canoe across a portage, I am also pretty good at estimating the distance which is measured in rods (16 feet, which is about the same length as a canoe). Voyaguers would measure distance traveled by smoking breaks

As pointed out many times before, Imperial units are useful because they can be related in handy objects.

It is not uncommon for German and Japanese companies to use kilograms-force instead of newtons, and horsepower, instead of watts, to describe thier products (yes, even on thier own internal documents).

As an engineer, I much prefer using metric for calculations, it's far easier to solve some problems in metric. but for problems that don't require a calculator, give me imperial units.

 

[BetterThanLife]

Actually Pounds to Tons is 2000. But the point of scalability is not lost on me. However in all honesty, conversions of scale is rare. Even when using the Metric system the scales aren't used all that often. For example the speed of light is generally listed as 3^8 meters/second. Why meters? Why not 3^5 Kilometers/second? You measure the size of your room in feet or meters but you measure the distance to work in Miles or Kilometers. You don't convert, you just measure it. (Yet Altitude and depth is measured in Feet or Meters, go figure.) You measure your weight in pounds or Kilograms, (Though why not Newtons is beyond me.) yet you measure food in grams or ounces. Again you don't convert you just measure. Convertability is an issue but it isn't an important consideration.

As far as Traveller goes though, consider this. The Solomani invaded and conquered the Imperium. Then the Second Imperium collapsed. Yet a standard day is still 24 hours and a standard year is 365 days, a standard month is 28 days. Those are the numbers for Earth's rotation, the Lunar orbital period and Earth's orbital period. Yet the period of rotation of Vland is 32 hours. And the entire empire was using the 32 hour day before the fall of the first Imperium. Then the Third Imperium was founded in the area between Vland and Terra. Yet standard time is based on Earth's time?

The Standard units of measure are SI units? Talk about ego centric.

(Especially since the French haven't won a war without US help since they created and adopted SI units.

) Hey maybe that explains that streak.

Sorry couldn't resist.

 

[Andrew Boulton]

"Yet standard time is based on Earth's time?"

I *think* Sylea's day/year are the same as Terra's.

"(Especially since the French haven't won a war without US help since they created and adopted SI units. )"

How many wars has the US won without French help?

 

[Fritz_Brown]

All but one of them?

 

[womble]

Bhoins:
The figure I used was probably a British imperial ton, then, (since it's the oz-lb-st-cwt-t progression) which is actually close enough (for engineering work) to a metric tonne. Another problem with Imperial units: there are two scales. I don't know whether US pints are the same as British, but I know the gallons are different, and I don't know which is used to measure the capacity of the 'barrel' which measures oil...

You're right about not often, in daily life, really wanting to convert from imperial to metric for single dimensional measurements (length, time, mass), but multidimensional measures (acceleration, power, energy, torque) are a different matter, and sicence (and games) have to deal with greatly varying scales. Whether you measure the acceleration of a vehicle in 'G', mph/s or fps/s is context based, and these scales are a lot easier to convert between in metric. Generic construction mechanics need to be able to deal handily with very wide scales.

The biggest bugaboo in such conversions is the hour/minute/second issue, and hours and minutes are not SI units.

As far as games go, whatever period they're set in, the rules have to use measures we Terrans are familiar with, or we end up having to perform yet another conversion to find out whether the bike we're using is a Piaggio or a Ducati, so there's little point defining game objects in some made up system. A corollary of this is that any flimsy excuse needs to be exercised by the designers to have the folk in the game milieu use a Terran system, so talk of metre/feet/hours isn't 'anachronistic'.

Measuring weight... I don't have a problem with us using measures of mass as opposed to force when referring to how much things 'weigh'. It's shorthand. What we're really interested in is almost always the mass of the object/material, which is the constant (to some peoples' eternal chagrin . 95 kg at 180cm is 'heavy built' (for a terran hume) whatever gravitational field you're in. A 16oz steak is either average or large depending on culture, but its nutrutional value doesn't vary according to the gravitational attraction it is experiencing. As I've said before, the distinction of mass vs force in 'weighing' only applies when using a spring balance, when what, in effect, you are doing is using an instrument that measures force and has a display calibrated to convert that force to mass for the gravitational field in which the balance will be presumed to be operating.

 

[BetterThanLife]

Originally posted by womble:
Bhoins:
The figure I used was probably a British imperial ton, then, (since it's the oz-lb-st-cwt-t progression) which is actually close enough (for engineering work) to a metric tonne. Another problem with Imperial units: there are two scales. I don't know whether US pints are the same as British, but I know the gallons are different, and I don't know which is used to measure the capacity of the 'barrel' which measures oil...

Pints are 16oz, 2 pints to a quart, 8 pints to a gallon. (Though few people use quarts these days.)

There are two gallons, one is 4 quarts the other is 4 liters. (Used, AFAIK, strictly in Canada, though it may be used in other members of the commonwealth.)A barrel is 55 gallons (at 8 pints per gallon). The two tons are 2000 pounds and 1000 kilograms (or 2200 pounds.) Your ton is one I have never heard of.)

You're right about not often, in daily life, really wanting to convert from imperial to metric for single dimensional measurements (length, time, mass), but multidimensional measures (acceleration, power, energy, torque) are a different matter, and sicence (and games) have to deal with greatly varying scales. Whether you measure the acceleration of a vehicle in 'G', mph/s or fps/s is context based, and these scales are a lot easier to convert between in metric. Generic construction mechanics need to be able to deal handily with very wide scales.

I wasn't saying people don't convert from Imperial to Metric. (Though they don't, that wasn't part of the point.) They don't convert, normally, within each system. People don't convert, in their daily lives from meters to kilometers, or feet to miles. (Or square meters to square kilometers, or cubic meters to cubic kilometers for that matter.)

The biggest bugaboo in such conversions is the hour/minute/second issue, and hours and minutes are not SI units.

Actually days, hours, minutes and seconds are SI units. As are degrees, minutes, seconds. If they weren't SI units then SI couldn't be used for much of anything.

As far as games go, whatever period they're set in, the rules have to use measures we Terrans are familiar with, or we end up having to perform yet another conversion to find out whether the bike we're using is a Piaggio or a Ducati, so there's little point defining game objects in some made up system. A corollary of this is that any flimsy excuse needs to be exercised by the designers to have the folk in the game milieu use a Terran system, so talk of metre/feet/hours isn't 'anachronistic'.

I agree. Though to think that SI units would actually survive contact with an advanced alien contact or even technological advances is a bit, shall we say egocentric on our parts.

Measuring weight... I don't have a problem with us using measures of mass as opposed to force when referring to how much things 'weigh'. It's shorthand. What we're really interested in is almost always the mass of the object/material, which is the constant (to some peoples' eternal chagrin . 95 kg at 180cm is 'heavy built' (for a terran hume) whatever gravitational field you're in. A 16oz steak is either average or large depending on culture, but its nutrutional value doesn't vary according to the gravitational attraction it is experiencing. As I've said before, the distinction of mass vs force in 'weighing' only applies when using a spring balance, when what, in effect, you are doing is using an instrument that measures force and has a display calibrated to convert that force to mass for the gravitational field in which the balance will be presumed to be operating.

Actually measuring mass makes more sense than weight once we get off this rock. While we are here they are about equal, in terms of usefulness, they might as well be equal as long as gravity remains about the same world wide. That isn't really the problem. The problem is in other applications of force. I hear things like KG of thrust on a regular basis. And that makes absolutely no sense. Unless it is some kind of massive thrust.

You can't just take pounds of force and multiply it by 2.2 and think, now we are using SI units, aren't we intellectuals! It doesn't work!!!

I am an American. (Actually more accurately a Native born US citizen.) You can drag me kicking and screaming into using SI units if everyone insists. But you can't say it is better just because I am allowed to multiply by 10. I buy my gasoline and milk in gallons (at 4 quarts a gallon) but I have to buy my alcohol, except beer, in liters, or multiples thereof. My car has a 3.1 liter engine, but the car I want to buy has a 427 cubic inch engine.

I understand the metric system. I spent 9 years active duty as an Army Interrogator. Our military maps are in kilometers, so our allies can read them, yet our speedometers are in miles per hour, and the Physical fitness test includes a 2 mile, not 3.2KM run. The rifle ranges are set up with targets at 50m, 100m, 150m, etc. but estimating range is taught as "how many football fields is it?" (At 100 yards each.) I had to understand on an instinctive level metric units, so I understand what an EPW was talking about when describing things like size and distance. And we talked about an objective being so many klicks away. Perhaps the German General had it right. "The reason the US military is so good is that war is chaos and the US military practises chaos on a daily basis."

I do understand the Metric or SI system. I understand its supposed strengths. The system isn't really any better. It is just another system of measures and is no more accurate than the system I use now. And parts of it are definitely misused and that makes no sense for a system that is supposedly superior. If it was so much better then the system would instinctively be used the right way. The other thing is the whole multiply by 10. If it was all based on 12 instead it would work better for units of measure that humans use on a regular basis. (It would make scientific calculations a little more difficult but scientific calculations haven't been calculated by hand in over 40 years.)

Perhaps we need a new system. Keep time. Using the speed of light as the basis for distance. Energy output of a hydrogen fusion reaction as the basis for energy. Then e=mc^2 would get us nice mass figures. F=ma using G as the basis for the accelleration number would get us a good weight basis. Temperature that nicely covers the normal human habital zone. I mean basing the system on those things makes more sense for a measurement system. Having it base 12 instead of base 10 makes normal use easier for the common man. Now how do I sell it?

 

[BetterThanLife]

Originally posted by Andrew Boulton:
"Yet standard time is based on Earth's time?"

I *think* Sylea's day/year are the same as Terra's.

"(Especially since the French haven't won a war without US help since they created and adopted SI units. )"

How many wars has the US won without French help?

I don't recall any French units involved in The Spanish American War, The Mexican American war, or The War of 1812. The Union won the Civil war without French assistance. More recently, I don't recall French participation in Grenada, Panama, or the actual liberation of Afganistan. (though there may be French forces helping keep the peace now.)They certainly didn't help liberate Iraq. (Though military operations pacifying the country are still ongoing so school is still out as to whether that can be considered a total victory.)

French military campaigns without US help since adoption of SI units. There was Napoleon, he lost twice. WWII, before US involvement, The French lost and surrendered, only to have French units dragged back into the war, after surrendering to the American forces in North Africa. Viet Nam, Algeria... enough said. Did I miss any?

 

[BetterThanLife]

Originally posted by Fritz88:
All but one of them?

And we inherited that mess from the French.

 

[Andrew Boulton]

There was a smiley there, but if you insist:

The USA probably wouldn't exist if it hadn't been for the French. They also helped (for varying values of "helped") with WW1, WW2, Korea, and Kuwait. I'll give you Grenada and Panama, but they barely count as wars.

 

[far-trader]

Rather than get into this I'll just innocently* ask what all "this" has to do with "Just what exactly is a G?" (you know, the thread topic ) and why it isn't being taken to the "Political Pulpit" as the proper forum for it. Thanks.

* Trust me, I know how easy it is for the topic to wander, especially if I post

 

[BetterThanLife]

Originally posted by far-trader:
Rather than get into this I'll just innocently* ask what all "this" has to do with "Just what exactly is a G?" (you know, the thread topic ) and why it isn't being taken to the "Political Pulpit" as the proper forum for it. Thanks.

* Trust me, I know how easy it is for the topic to wander, especially if I post

Back on topic. The value of a G is 32.2 feet per second squared.

 

[womble]

Tons:

British Imperial, Bhoins? That's what sort of ton I was talking about, as I said.

Volume:
Pints are 20floz where I come from, but a quart is still 2 pint and a gallon is 4 quarts.

Conversions:
I disagree that people don't convert from smaller to larger units. I often find myself converting when a scale I don't think is appropriate for the physical scale being measured has been used: mm in furniture, for example, I convert to centimetre in my head, because it matches the scale better (300mm kitchen units for example in a 5mx4m room). And if you take that into imperial, you have 24inch units, with inch clearance in a 15ftx12ft room. And you have to work out how many square feet of floor tiling you need. There are conversions done all the time. Pints to gallons (possibly via quarts) will happen all the time in the bulk milk industry. And that will need converting into ton for transportation.

How about lengths less than 1 inch? Measured in fractions, yes? Quarters, halves, eighths, sixteenths and thirtysecondths? Real easy to add up, especially for people who don't even begin to understand fractions, and there're plenty of them about.

Time and angle:
http://physics.nist.gov/cuu/Units/units.html
The SI unit of time is the second. Hours, minutes and days are 'units accepted for use within the SI' http://physics.nist.gov/cuu/Units/outside.html
Ditto degrees and arc-minutes and arc-seconds. The SI unit of (plane) angle is the radian.

Mass/weight:
I'm sorry, but you don't seem to be reading what I've said. Measuring mass is the only thing that makes sense (when we're talking about how much of something there is). The fact that we can use something's weight in a known gravitational field to determine its mass is a consequence of the invention of spring balances. And the confusion of mass with weight is a relict of ancient pre-Newton world models, maintained by our broad inability to experience a world where mass and weight are not inextricably proportional for a given object.

"...I hear things like KG of thrust on a regular basis..."
You can't blame this system for this misuse. If people are sloppy about the difference between mass and force, then no system of measurement is going to make (I avoided using the word 'force, there... them to draw the distinction. At least SI has different units for mass and force, or, at least, I've never heard anyone distinguish between the 'pound' used for thrust and the 'pound' of cast iron used to balance out my apples on an old fashioned grocer's scale when I was younger.

Hodgepodge:
You can't blame the SI system for the current hodgepodge of units in people's heads. Yes, I still measure how far I drove over Christmas in miles, the speed limits are in mph, and I use feet and metre largely interchangably. Doesn't mean I think Imperial is better. Science uses SI for good and valid reasons of interchangeability, and common usage should follow. Ooh. Just thought of a conversion: How much does a pint of water weigh? It's not 'a pound'. In looking up the answer, I found this: http://www.ofb.net/~jlm/oracle/oracle.365.10

I am entirely at liberty to say it's better because I can multiply by tem. Countries with decimal coinage systems seem to think so too, for the most common arithmetical operation conducted in any country. How is it 'better' to have various multiples of 3, 2, 8, 12 and 1760 for smaller units to scale to the larger? How is even 'as good' a system?

"...I do understand the Metric or SI system. I understand its supposed strengths...."
I really don't think you do. You have a solid grasp of how far a km is, and how much a litre is, perhaps, but have you ever converted energy per second for however long into total energy expended, using imperial measures? And then seen how easy it is at any scale in SI?

Scalability and interoperability make the SI a system that works better across the whole of human experience and observation, from femtometre on up than using Imperial measurements which don't have a system.

New system:
Only of use if the old one is broken, and the people who use the system the most (scientists) don't seem to think it is. The only way you'll poularise a base 12 counting system is by getting the human species to sprout an additional digit on their extremities. We count in tens because we're lazy.