8th Grade Test (If You Dare!)

[tedro]

[quote]matko5 wrote:

1. why would I do that? 1/32’’ is to small for a tape measure, if you can see than fine gradation you have a better than hawk eye my friend.
   [/quote]
   Uhhh, not even close. Every decent tape measure has 1/32" graduations. I can usually get within +/-.010" with a good tape, which is well within 1/64".

If you want to divide and inch 5 times in half, in centimeters you’d get 0,08cm, that’s 0.8mm.

LOL, really? I didn’t even ask you to cut an inch in half, I said cut a cm in half. Even so, you won’t come up with .8mm either way.

2. Again, to small for anything you’d use in construction or engineering with a tape measure, then best you can do is to a 0.5mm. Let me put it to you like this: for every inch in a tape measure, there are 25.4 markings on a milimeter scale. You don’t need fractions, you can get almost exact results (I need to cut 14mm from this plank) instead of fractions (I need to cut 1/8’’ from this plank). I may not come from construction background, but I’ve watched my father numerious times building or fixing something.

Wait, are you telling me you’ve never even used the imperial system? You asked what its purpose was, then went on to disparage it when you have absolutely no basis for your statements. Fractions can be a real virtue outside of your textbook world. Perhaps you should use both next time before you claim one to be worthless.

I never claimed the metric system can’t be precise. Precision is solely dependant on the measuring instrument. Where the metric system lacks is its ability to easily divide, you are basically forced to use decimal notation at all times, and not many people are real good with dividing and multiplying decimals in their head, which you showed in your last post.

By the way, do you use a metric clock too? Or do you divide your day into 24 equal parts? Do you think this number just came about randomly, or that just maybe it worked out as a very convenient multiple? How about minutes or seconds? Why 360 degrees in a circle? Shouldn’t all of these arbitrary numbers be some sort of base-10 system?

[Bill_Roberts]

There actually was an attempt to have the metric system to employ decijours, centijours, millijours, etc, but it didn’t succeed.

[matko5]

[quote]tedro wrote:

[quote]matko5 wrote:

1. why would I do that? 1/32’’ is to small for a tape measure, if you can see than fine gradation you have a better than hawk eye my friend.
   [/quote]
   Uhhh, not even close. Every decent tape measure has 1/32" graduations. I can usually get within +/-.010" with a good tape, which is well within 1/64".

If you want to divide and inch 5 times in half, in centimeters you’d get 0,08cm, that’s 0.8mm.

LOL, really? I didn’t even ask you to cut an inch in half, I said cut a cm in half. Even so, you won’t come up with .8mm either way.

2. Again, to small for anything you’d use in construction or engineering with a tape measure, then best you can do is to a 0.5mm. Let me put it to you like this: for every inch in a tape measure, there are 25.4 markings on a milimeter scale. You don’t need fractions, you can get almost exact results (I need to cut 14mm from this plank) instead of fractions (I need to cut 1/8’’ from this plank). I may not come from construction background, but I’ve watched my father numerious times building or fixing something.

Wait, are you telling me you’ve never even used the imperial system? You asked what its purpose was, then went on to disparage it when you have absolutely no basis for your statements. Fractions can be a real virtue outside of your textbook world. Perhaps you should use both next time before you claim one to be worthless.

I never claimed the metric system can’t be precise. Precision is solely dependant on the measuring instrument. Where the metric system lacks is its ability to easily divide, you are basically forced to use decimal notation at all times, and not many people are real good with dividing and multiplying decimals in their head, which you showed in your last post.

By the way, do you use a metric clock too? Or do you divide your day into 24 equal parts? Do you think this number just came about randomly, or that just maybe it worked out as a very convenient multiple? How about minutes or seconds? Why 360 degrees in a circle? Shouldn’t all of these arbitrary numbers be some sort of base-10 system? [/quote]

1/32 of a centimeter is 1/32 of a centimeter, as is 1/32 of an inch is a 1/32 of an inch. I have no clue what your point is. The only difference in metric system you wouldn’t express that in centimeters anymore, but in something smaller.

[tedro]

[quote]matko5 wrote:
1/32 of a centimeter is 1/32 of a centimeter, as is 1/32 of an inch is a 1/32 of an inch. I have no clue what your point is. The only difference in metric system you wouldn’t express that in centimeters anymore, but in something smaller.[/quote]

The point is exactly that. Nobody writes centimeters as 1/32, you put it in decimal notation, but a 32nd, which is a very natural fraction, doesn’t fit very well as a decimal does it?

[Hellfrost]

[quote]tedro wrote:

[quote]matko5 wrote:
1/32 of a centimeter is 1/32 of a centimeter, as is 1/32 of an inch is a 1/32 of an inch. I have no clue what your point is. The only difference in metric system you wouldn’t express that in centimeters anymore, but in something smaller.[/quote]

The point is exactly that. Nobody writes centimeters as 1/32, you put it in decimal notation, but a 32nd, which is a very natural fraction, doesn’t fit very well as a decimal does it?[/quote]

Are you seriously comparing the Metric system to the Imperial system? The metric system is used due to it’s ability of ease to convert from one unit to another. In a second I can convert 25,453,000mm to km (25.453km if you are interested). Now try converting 25,453,000 inches to miles without a calculator, ill wait.

Every scientific experiment that requires measuring usually involves the metric system. The only thing I can see about the imperial system is that pounds has calculated force in the equation i.e. 100 pounds on earth is 100 pounds on the moon, while 100 kg on earth is 16.6 kg on the moon.

[3hitter]

See the metric system does have it’s flaws…

Not just on the moon.

If I tell you a woman is 36-24-36. Everyone understands that.

But if I say the same woman is 914.4-609.5999999-914.4, well that just doesn’t work.

[Bill_Roberts]

Um, no, 100 kg is 100 kg whether on Earth, on the Moon, or in space.

The only difference between customary units and metric in this regard is that “pound” refers both to mass and to force, while kg properly refers only to mass (the unit of force is the newton.)

EDIT: Yes there are later constructs of “pound-force” and “pound-mass” to make distinctions, but one scarcely ever sees them in print and I don’t think I’ve ever heard them spoken. The word “pound” tends to be used for either force or mass, with context determining the intended meaning.

[matko5]

[quote]Hellfrost wrote:

[quote]tedro wrote:

[quote]matko5 wrote:
1/32 of a centimeter is 1/32 of a centimeter, as is 1/32 of an inch is a 1/32 of an inch. I have no clue what your point is. The only difference in metric system you wouldn’t express that in centimeters anymore, but in something smaller.[/quote]

The point is exactly that. Nobody writes centimeters as 1/32, you put it in decimal notation, but a 32nd, which is a very natural fraction, doesn’t fit very well as a decimal does it?[/quote]

Are you seriously comparing the Metric system to the Imperial system? The metric system is used due to it’s ability of ease to convert from one unit to another. In a second I can convert 25,453,000mm to km (25.453km if you are interested). Now try converting 25,453,000 inches to miles without a calculator, ill wait.
[/quote]

This.

[Hellfrost]

[quote]Bill Roberts wrote:
Um, no, 100 kg is 100 kg whether on Earth, on the Moon, or in space.

The only difference between customary units and metric in this regard is that “pound” refers both to mass and to force, while kg properly refers only to mass (the unit of force is the newton.)[/quote]

My mistake, you are correct. I din’t do all that well in physics anyway haha.

[tedro]

[quote]matko5 wrote:

[quote]Hellfrost wrote:

[quote]tedro wrote:

[quote]matko5 wrote:
1/32 of a centimeter is 1/32 of a centimeter, as is 1/32 of an inch is a 1/32 of an inch. I have no clue what your point is. The only difference in metric system you wouldn’t express that in centimeters anymore, but in something smaller.[/quote]

The point is exactly that. Nobody writes centimeters as 1/32, you put it in decimal notation, but a 32nd, which is a very natural fraction, doesn’t fit very well as a decimal does it?[/quote]

Are you seriously comparing the Metric system to the Imperial system? The metric system is used due to it’s ability of ease to convert from one unit to another. In a second I can convert 25,453,000mm to km (25.453km if you are interested). Now try converting 25,453,000 inches to miles without a calculator, ill wait.
[/quote]

This.[/quote]

Show me where I said that the metric system doesn’t also have its benefits.

It is the metric fanboys here that are too ignorant to realize there is a place for both systems.

[Bill_Roberts]

There’s sort of a strange disparity here.

On the one hand, we have “Are you INSANE? You actually think someone should know that there are 2.54 centimeters in an inch, or if not that then at least ONE way to interrelate the units, such as km per mile or inches per yard? Oh that is MEMORIZATION! Stupid!”

And then we have those who probably almost exclusively use inches and pounds extolling the metric system and working hard to deny that there could be ANY advantage to US customary units (or Imperial as the case may be.)

[buffalokilla]

[quote]Bill Roberts wrote:
The only difference between customary units and metric in this regard is that “pound” refers both to mass and to force, while kg properly refers only to mass (the unit of force is the newton.)

EDIT: Yes there are later constructs of “pound-force” and “pound-mass” to make distinctions, but one scarcely ever sees them in print and I don’t think I’ve ever heard them spoken. The word “pound” tends to be used for either force or mass, with context determining the intended meaning.[/quote]

Imperial units

also Slug (unit) - Wikipedia

Interesting, so if the modern usage of pound is for both force and mass, that means neither of the measures are ever correct unless an object is perfectly at sea level.

[ds1973]

As an R&D engineer, who is currently writing a recommendation for a plant upgrade in both sets of units, I’m laughing at all this.

Some people use metric, some use imperial. Our pilot plant has pressure in psig, temperature in C, flow in standard cubic feet per minute (NTP as opposed to STP). I suppose we can’t do scientific experiments in it because it’s not instrumented to read in all metric.

In the real world, you’re going to run into both. For the units you deal with a lot, you’ll memorize by necessity. For example, 14.696 psia = 101325 Pa. F = C *9/5 + 32. 1 in = 0.0254 meters. The ideal gas constant (in the units I use) is 8.314 Pa-m3/mol-K - all from memory because I use them so much.

[Bill_Roberts]

[quote]buffalokilla wrote:

[quote]Bill Roberts wrote:
The only difference between customary units and metric in this regard is that “pound” refers both to mass and to force, while kg properly refers only to mass (the unit of force is the newton.)

EDIT: Yes there are later constructs of “pound-force” and “pound-mass” to make distinctions, but one scarcely ever sees them in print and I don’t think I’ve ever heard them spoken. The word “pound” tends to be used for either force or mass, with context determining the intended meaning.[/quote]

Imperial units

also Slug (unit) - Wikipedia

Interesting, so if the modern usage of pound is for both force and mass, that means neither of the measures are ever correct unless an object is perfectly at sea level.[/quote]

On mass, yes, if one attempts to determine mass with a balance, which in fact measures downwards force caused by the weight of the object, it is necessary for the balance to be calibrated to the local gravitational field. This can be done by having reference standard weights.

As for the force of one pound, it is the same amount under any gravity conditions. In other words, the definition isn’t dependent on what the weight of an object massing one lb would be in the conditions at hand.

So, if you have a piece of steel with a mass of 1 lb, it would weigh precisely 1 lb on a scale only if the scale’s calibration was adjusted for the local gravitational field.

The “weight” it would exhibit would be a force differing from one pound-force unless gravity was exactly the standard value.

The same situation exists in the metric system except that if, as physicists do, one avoids using kg for force but instead uses Newtons, at least the two concepts don’t get confused – and units cancel out correctly in calculations.