? For math & physics guys

Originally posted by KellyJay
9 feet or 12 feet, my back and legs would be killing me either way!
Kelly

To say nothing of our feet....

Originally posted by USArmyParatrooper
The rate of descent for the T-10D parachute is 22 - 24 feet per second.

What elevation is that equivalent to jumping off of without a parachute?

And see this is why you smacked a probe strait into Mars...

SI units people... That's what we do science in.

😛

Originally posted by googlefudge
And see this is why you smacked a probe strait into Mars...

SI units people... That's what we do science in.

😛

Not really, each field has its own units of convenience, some of which are SI and some aren't. In fundamental physics they use units where those fiddly constants that don't really tell you much are all set to 1, so the equations tell you what the relations between variables are and aren't just dominated by arbitrary parameters. The electron volt is a convenient unit to fix the energy scale and everything else.

One point where the old system is actually better is pedagogically. Newton's second law is often expressed as F=ma. Kid's get pedantic about this. However the canonical expression of Newton's second law is that Force is proportional to the rate of change of momentum. Assuming the mass doesn't change you have F=kma, and then you can pick units to have the constant of proportionality equal to one. What I'm getting at is that the basic relationship is one of proportionality, the units system is then chosen to hide the constant to make practical calculations easier. The constant is still there though, its needed to convert m/s^2 into Newtons.

In Europe anyone doing any engineering does it in SI units, but in the U.S. they may be better off sticking with imperial units for safety critical problems because that's the system that's intuitive to their engineers. It depends on whether the cumulative losses such as Hubble's mirror are greater than the risk of carnage on a switchover.

Originally posted by DeepThought
Not really, each field has its own units of convenience, some of which are SI and some aren't. In fundamental physics they use units where those fiddly constants that don't really tell you much are all set to 1, so the equations tell you what the relations between variables are and aren't just dominated by arbitrary parameters. The electron volt is a c ...[text shortened]... losses such as Hubble's mirror are greater than the risk of carnage on a switchover.

Yeah, I know. I studied physics at uni...

I was just poking fun.

I would say more seriously though that it would probably be worth it from a compatibility standpoint given that pretty much everyone else uses SI units in engineering.

For example, NASA's requirement that the new international standard for docking ports is in imperial rather than metric is causing problems for every non US team, and for anyone wanting to source components from outside the USA.


And given that if you want an 'intuitive feel' for something it's pretty trivial to convert back to imperial if you have a hard time visualising stuff in meters.

For example when the scientists at CERN were discussing the apparently FTL neutrino problem they were doing all the measurements in SI units... but when they wanted an intuitive feel for which was likely to be the dominant error (distance measurement or time) they used the handy fact that light travels at about 1 foot per nano-second.


Imperial units are handy when dealing with human scale things, I always give my hight in feet and inches for example... and our garden fence is 6 feet high not however many centimetres...

But when doing precision engineering and science I really think you need to convert to standard units and become more compatible with the rest of the world.
Perhaps if you did the switch in the education system so that the next generation works in metric/SI.


Anyhow... as I say, my first post was mainly just poking fun.

Originally posted by googlefudge
Yeah, I know. I studied physics at uni...

I was just poking fun.

I would say more seriously though that it would probably be worth it from a compatibility standpoint given that pretty much everyone else uses SI units in engineering.

For example, NASA's requirement that the new international standard for docking ports is in imperial rather than m ...[text shortened]... ation works in metric/SI.


Anyhow... as I say, my first post was mainly just poking fun.

If it's causing problems the US should probably change. It might be worth insisting if it starts to turn into some type of protectionist move, which what you describe NASA doing sounds like.

As you do I tend to use feet, inches, pounds and stone, in daily life - partly out of contrariness and partly out of wanting to separate stuff I do professionally (I'm a programmer these days, but units are relevant) from when I'm at work, but not Fahrenheit I don't have any intuition for the scale. Incidentally, in your last paragraph you seemed to be implying that I was American, I have the Antarctic flag up as it entertains me to have it, but I'm English.

Originally posted by DeepThought
If it's causing problems the US should probably change. It might be worth insisting if it starts to turn into some type of protectionist move, which what you describe NASA doing sounds like.

As you do I tend to use feet, inches, pounds and stone, in daily life - partly out of contrariness and partly out of wanting to separate stuff I do professionall ...[text shortened]... was American, I have the Antarctic flag up as it entertains me to have it, but I'm English.

Hmmm...

I don't see any flags...

I think they may be being blocked by my adblocking software.