Mountain Project Logo

where did KN come from?

Original Post
yeego · · Unknown Hometown · Joined Apr 2011 · Points: 35

Does anyone know the history of kilo newtons (KN)? Where? How? When?

Appreciate it.

Carl Sherven · · Unknown Hometown · Joined Dec 2007 · Points: 210
Newton's are a unit of force, named after Isaac Newton. A kilo-Newton is 1000 Newtons. Isaac Newton was the founding father of classical mechanics, so the base unit of force was named after him. He was a giant among giants in the scientific community, arguably one of the greatest mathematical/scientific minds that ever lived. His work has positively impacted the lives of everyone that benefits from any type of modern living.

I guess that covers the "why," which you didn't really ask for. I hope that was useful.
Jim Titt · · Germany · Joined Nov 2009 · Points: 490

Introduced in 1960 under the SI unit system, previously the kilogram force (kgf) was used.

Bobby Hanson · · Spokane, WA · Joined Oct 2001 · Points: 1,230

A good approximation for 1 kN is 225 lbf, the weight of a big guy.

A good approximation for 1 newton is the weight of an apple. Appropriate, given the folklore surrounding Isaac Newton and his formulation of the Theory of Gravity.

To expand on what Jim has said above, 1 newton (N) is the force required to accelerate 1 kilogram by 1 m/sec^2. 1 kN is, of course, 1000 of these. 1 kgf is about 10 newtons (really, it is 9.80665 N); it is the weight of a 1 kg mass on Earth.

In case you are curious, a good approximation for 1 kilogram is the mass of 1 liter of water. And 1 liter is approximately the same as 1 quart. So that Nalgene you have carries about 1 kilogram of water (but only 9/10 of a kilogram of whiskey, BTW).

But maybe you were really asking why our (American) climbing gear is stamped with ratings in kN? The answer to that is because UIAA is located in Switzerland.

Now a harder question: where did pounds come from? :) What a stupid measurement. 1 lb = 6992 troy grains. WTF?

Mike Lane · · AnCapistan · Joined Jan 2006 · Points: 880
The Bobby wrote:A good approximation for 1 kN is 225 lbf, the weight of a big guy.
So if I jump up, I land with the force of 1 Kn? Or do I need to reach terminal velocity?
Also, I'll bet the pound is something like the weight of a criminal's hand after being chopped off.
DannyUncanny · · Vancouver · Joined Aug 2010 · Points: 100

Well like others said, one newton is equal to a kg meter per second squared. Seconds are defined by the frequency of cesium atoms. The kilogram is a kind of arbitrary mass roughly related to the density of water but actually defined by a platinum bar in Paris. The problem with that of course is that the bar is slowly losing mass. It's miniscule but still enough to be a worry for very precise physics.,

Mark Byers · · Unknown Hometown · Joined Sep 2011 · Points: 50
The Bobby wrote:Now a harder question: where did pounds come from? :) What a stupid measurement. 1 lb = 6992 troy grains. WTF?
1 lb = 1 (slug * ft)/s^2

Now, what the heck is a slug?
Louis Eubank · · Portland, ME · Joined Nov 2008 · Points: 181

Mike - It depends on how high you jump. If you have a 37" vertical jump, you should probably try out for the NBA. Otherwise, you would not land w/ a 1 N force. Jumping off anything elevated, however, would quickly get you into multiple N (since its m/s^2).

Yeego - The primary reason for using kN is, as has been stated above, it is a measure of force, hence much more useful in dynamic situations than kg (or lbs) would be. Another Newton fact is that he was one of the inventors of calculus.

DrApnea · · Wenatchee, WA · Joined May 2011 · Points: 265
Louis Eubank wrote:The primary reason for using kN is, as has been stated above, it is a measure of force, hence much more useful in dynamic situations than kg (or lbs) would be.
Dont you mean that it is more useful than kg (or slugs) since lbs is a measurement of force.
mike h · · Front Range, CO · Joined Jun 2010 · Points: 24
Mike Lane wrote: So if I jump up, I land with the force of 1 Kn? Or do I need to reach terminal velocity? Also, I'll bet the pound is something like the weight of a criminal's hand after being chopped off.
1 kN is the about the same as a 225lb weight hanging free on a rope, or you(at 225 lbs) standing on the ground. When you jump, or with any dynamic load, things get more complicated. It's not a function of how far you fall as Louis E said, but rather how quickly you slow down. The key point to remember is: F=ma. Your mass is constant, but depending on how much you bend your knees and back, what surface you land on, shoes you're wearing, etc, the acceleration (and therefore force) will vary significantly.

Someone summarized the point well by saying: "no one ever got hurt by driving fast, only stopping fast."
Dobson · · Butte, MT · Joined Oct 2011 · Points: 215
DrApnea wrote: Dont you mean that it is more useful than kg (or slugs) since lbs is a measurement of force.
Despite what we learned in school, the pound avoirdupois is now defined as a unit of mass, (since 1959, apparently). The standard is actually based on the kilogram.
JesseT · · Portland, OR · Joined May 2011 · Points: 100
DannyUncanny wrote:Well like others said, one newton is equal to a kg meter per second squared. Seconds are defined by the frequency of cesium atoms. The kilogram is a kind of arbitrary mass roughly related to the density of water but actually defined by a platinum bar in Paris. The problem with that of course is that the bar is slowly losing mass. It's miniscule but still enough to be a worry for very precise physics.,
The Pt bar is currently used as the standard for the SI kg, but a metric kg (which is equal in mass to the SI kg) was originally defined as the mass of 1 liter (1 dm^3) of water at 4 degrees C (the temperature at which water is most dense). A gram was originally defined by the mass of a cm^3 of water which is the same as a ml. Metric is pretty cool the way the units of mass, length and volume are all in terms of one another. Interestingly, the L is not an SI unit.

In the American system of measurement there's a slight correlation between volume and weight. A fl oz of water weighs approximately one ounce, which puts a pint at about one lb.

As to the issue of the Pt bar degrading over time, the CIPM is planning to redefine the kg in terms of the Planck constant.
camhead · · Vandalia, Appalachia · Joined Jun 2006 · Points: 1,240
The Bobby wrote: Now a harder question: where did pounds come from? :) What a stupid measurement. 1 lb = 6992 troy grains. WTF?
Relic from England, which even England has gotten rid of, but the US is too conservative to give up. Kind of like how England abolished slavery a generation before we did.
Will S · · Joshua Tree · Joined Nov 2006 · Points: 1,061
muttonface wrote:You guys are some smart, fairly well educated sunzabitches.
Engineering 101, actually high school physics 101, but I'd bet a shitload* of us are engineers or similar. (* shitload= 624896 x 10^-4)
Michael Dupont · · Woodbury, MN · Joined Sep 2008 · Points: 30

It has always struck me as odd that the English system uses pounds as a weight (which is correct) but metric, which so wonderfully meshes together and is pretty much superior, uses a description of mass (kilograms) sometimes interchangeably with weight (newtons).

How much do you weight? xxx lbs is correct. xxx kilograms is wrong. xxx newtons is correct.

And as far as a stupid unit of measure. Rods and Stones.

Martin le Roux · · Superior, CO · Joined Jul 2003 · Points: 401
shuminW wrote:I think while the metric system is superior for scientific purposes, English system has advantage for everyday uses: what's 1/8 of a lb? 2 ounces. what's 1/8 of a kilograms? 125 grams. What's 1/3 of a foot? 4 inches. what's 1/3 of a meter? 33.3333.... centimeters??? Can you imagine using a decimal system for time in place of what we have now?
Clearly this speaks to the advantages of the furlong-firkin-fortnight system of measurement. What's 1/11 of a furlong? 20 yards. What's 1/9 of a firkin? 10 lbs. What's 1/7 of a fortnight? 48 hours. Just try that with plain old feet, pounds or seconds.
Michael Dupont · · Woodbury, MN · Joined Sep 2008 · Points: 30
Martin le Roux wrote: What's 1/9 of a firkin?
I'm pretty sure that's 20 seconds.

Oh wait, you wrote firkin? No idea what that is.
John Maguire · · Boulder, CO · Joined Nov 2008 · Points: 195
Mike Lane wrote: So if I jump up, I land with the force of 1 Kn? Or do I need to reach terminal velocity? Also, I'll bet the pound is something like the weight of a criminal's hand after being chopped off.
Mostly depends what kind of shoes you are wearing.
grampa potate · · Unknown Hometown · Joined Dec 2011 · Points: 5

I measure force in Chuck Norris units.
The only problem with this is that 1 CN equals infinitely many pounds (or Kilonewtons for that matter)...so it's a fairly big unit. So, I should choose to use MicroCN, but that's also an infinite unit...shoot

JesseT · · Portland, OR · Joined May 2011 · Points: 100
shuminW wrote: ...English system has advantage for everyday uses: what's 1/8 of a lb? 2 ounces. what's 1/8 of a kilograms? 125 grams. What's 1/3 of a foot? 4 inches. what's 1/3 of a meter? 33.3333.... centimeters??? Can you imagine using a decimal system for time in place of what we have now?
I've been making this argument for years, but my geophysicist girlfriend and my engineer friends don't agree.

The English system is based (within a unit anyway) on halves. Take a piece of paper and fold it in half. Easy, right? Now fold it into quarters. Also easy. Take another piece of paper and fold it into 10 equal sections. Wait, what?

Also, for height: How tall are you? Six feet two. The feet unit gives a ballpark measure, the inches unit fine tunes it. How tall are you? One point eight eight meters (or one-hundred eighty-eight centimeters). You're forced to spit out all your precision at once.

I also like the idea of using different units for different scales (in for small stuff, miles for big stuff). I can't quite explain why though.

Now, for base ten calculations and unit conversions metric (sorry, it's SI now) is far superior. In reality I use both. If something's about a cm, I use cm, if it's about an inch I use inches. I shoot 9mm and .45acp.
slim · · Unknown Hometown · Joined Dec 2004 · Points: 1,103

interestingly enough a newton is approximately the weight of an apple, give or take. or so i've heard....

Guideline #1: Don't be a jerk.

General Climbing
Post a Reply to "where did KN come from?"

Log In to Reply

Join the Community

Create your FREE account today!
Already have an account? Login to close this notice.

Get Started.