PDA

View Full Version : KN/m2 ???

Unregistered
05-13-2006, 10:00 AM
How do i work out KN/m2, can anyone help???

Thanks.

Dave.

Robert Fogt
05-14-2006, 04:31 PM
Can you provide more information as to what you are trying to do?

You need to convert that to something else, or convert something else to that?

Unregistered
07-22-2007, 10:34 AM
what does Kn/m2 mean in context to the weight of a dead load....i.e. a house?

Robert Fogt
07-22-2007, 12:03 PM
It's a unit of pressure, force per area. For a weight such as a house it would be how much weight over a specific area.

kN = kilonewton, a unit of force.
m2 = mē = square meter, a unit of area

kN/mē = kilonewton/square meter

You can convert kilonewtons to pounds-force or kilograms-force, if that will make it easier to understand.

Unregistered
10-16-2007, 07:11 AM
so if is stated that the floor can support 100KN/m2, it means it can handle a average weight of 100kg per m2?

Roy Nakatsuka
10-17-2007, 10:04 PM
Unfortunately, it's not quite that simple.

One newton is approximately equal to one-tenth of a kilogram (0.1 kg). Since the floor you're describing can support 100 kN/m2, that's 100,000 N/m2, or 10,000 kg/m2. So the floor would be 100 times stronger than you thought.

Hope that makes you feel safer! :)

Mrs X
10-17-2007, 11:31 PM
Unfortunately, it's not quite that simple.

One newton is approximately equal to one-tenth of a kilogram (0.1 kg). Since the floor you're describing can support 100 kN/m2, that's 100,000 N/m2, or 10,000 kg/m2. So the floor would be 100 times stronger than you thought.

Hope that makes you feel safer! :)
Opps, 1 newton = 9.8 kg (force) :D

This is derived by the weight in kilograms, times the force of gravity. I learned that here, from a poster called.... um....

and then we've been using it all the time at work, since.

Roy Nakatsuka
10-18-2007, 01:42 AM
Surely you're joking, Mrs X! *

But I don't know your sense of humor well enough to be sure. On the chance that you are serious, please read the last line of Post #9 in the following thread, to which I believe you are referring--
"To convert from kilogram-force (kgf) to newton (N) Multiply by 9.80665"
In equation form, that statement says:
1 kgf = 9.80665 N
Or, inverting,
1 N = 1/9.80665 kgf = 0.101972 kgf
Now, on the chance that you really were serious, I will let you claim that you were joking, as even Einstein was known to have made mistakes, and your good works in this forum have surely earned you many free passes from all.... :) :) :)

But please, please assure me that you haven't really been using your stated formula at work!? :eek: :eek: :eek:

Oh, and one more item of important business--To both you and janiceruth, my sincere apologies for bulldozing you in that earlier thread, but I was terribly concerned about that poor school student picking up an incorrect answer and remembering it for the rest of his/her life! And then having other people also read it without correction. We wouldn't want the same thing to happen in the current thread either, now would we? :o

So, I repeat my assertion:
1 N = 0.1 kg (approximately)
and I claim that this is equivalent to what I posted in that earlier thread. :)

* In case you didn't catch the pun in my greeting, it comes from the title of a delightful book about... a physicist! Imagine that!

Mrs X
10-18-2007, 10:38 AM
Oh duh! We discussed it, and still I got it wrong! I should stick to chemistry, and not worry about physics.

1kg gives 9.8 Newtons. Most people just multiply weight (in kg) by 10 to get newtons.

Roy Nakatsuka
10-19-2007, 06:47 AM
Dear Mrs X,

1kg gives 9.8 Newtons. Most people just multiply weight (in kg) by 10 to get newtons.
That's an excellent summary you've provided, which will be useful to everyone. I know that you actually understand the concepts very well.

The anecdotes below at another website should certainly remind you of the value of the kind of help you provide to others in this forum! :)

I am a Physics teacher at The International School of Bucharest.... It happened in my class..
'we were talking about the acceleration of free-fall. I wrote a 'g' letter on the board, and asked 'How can we measure this constant? Do you have any idea?' One of them stood up, came to the board, and measured the length of the 'g' letter on the board, and said 'by a ruler, teacher!'
Early morning Physics class filled with slightly dazed freshmen. Eager beaver post-doc teaching the class asks "The wavelength of the Sodium yellow line. What is it? You there!"

Fortunately he has his eagle eye on the guy next to me, who mutters: oh ****, and replies "A hundred and one?"

"Hah!" says the postdoc "A hundred and one what?"

"Um, a hundred and one, point two?"

Robert Fogt
10-19-2007, 04:57 PM
ah HAHAHAHAHAHAHA :rofl:

So its ok to laugh at those right?

Roy Nakatsuka
10-20-2007, 11:19 AM
Yes. In fact, the punishment for not laughing is ten lashes. :whip:

But it's only fair to look at things the other way, too --
*** "You might be a scientist if..." ***You ever burned down the gymnasium with your Science Fair project.

The salespeople at Circuit City can't answer any of your questions.

You have a one-hour debate about the result you expect from a test that takes five minutes to run.

The microphone at a meeting doesn't work and you rush up to the front to fix it.

You've used coat hangers and duct tape for something other than hanging coats and taping ducts.

Your three-year-old child asks why the sky is blue and you try to explain atmospheric absorption theory.
Oh, and one more:
Q: How many physicists does it take to change a light bulb?
A: Two. One holds the bulb, while the other rotates the universe. :rofl:

Mrs X
10-20-2007, 01:20 PM
Yes. In fact, the punishment for not laughing is ten lashes. :whip:

But it's only fair to look at things the other way, too --
*** "You might be a scientist if..." ***You ever burned down the gymnasium with your Science Fair project.

The salespeople at Circuit City can't answer any of your questions.

You have a one-hour debate about the result you expect from a test that takes five minutes to run.

The microphone at a meeting doesn't work and you rush up to the front to fix it.

You've used coat hangers and duct tape for something other than hanging coats and taping ducts.

Your three-year-old child asks why the sky is blue and you try to explain atmospheric absorption theory.
Oh, and one more:
Q: How many physicists does it take to change a light bulb?
A: Two. One holds the bulb, while the other rotates the universe. :rofl:

I heard about someone who filled a very early turbo pumped vacuum system with water, by operating the valves in the wrong order. :)

Unregistered
09-25-2008, 09:29 AM
How do i work out KN/m2, can anyone help???

Thanks.

Dave.
One newton (N) is the force needed to accelerate 1 kilogram by 1 meter per second squared. Since the acceleration of gravity is 9.8 meters per second squared on earth, that means that a mass of 1 kg is exerting a force of 9.8 N when at rest. (This is a fundamental difference between metric and English units: in metric, you use different measures for mass and force, while in English you use pounds for both mass and force -- which can be terribly confusing!)

So converting to English units, a weight of 1 kg (mass) exerts 9.8 newtons (of force), which is the equivalent of 2.2 pounds (of force). So 4.45 newtons is 1 pound. Then 15kN, or 15000 newtons, is 3371 pounds.

That weight is distributed over 1 square meter. Since 1 foot = .3048 m, 1 square foot is .092903 square meters. Multiplying the weight by this number gives us
15 kN/m2 = 3371 * .092903
= 313 pounds per square foot

Unregistered
10-16-2008, 11:53 AM
I still dont understand about the way you work it out. for example, if the floor is 20cm thick and the density of the floor is 2500kH/m3 wot formula would you use????

Unregistered
04-25-2010, 06:32 AM
Can you provide more information as to what you are trying to do?

You need to convert that to something else, or convert something else to that?

I am trying to work out the weight linit of 30kn/m2

JohnS
04-25-2010, 08:06 AM
I am trying to work out the weight linit of 30kn/m2

I answered with a more detailed response in your other thread, but about 3000 kg/mē, assuming a deadweight or static load.

Mr.Engineer
07-16-2010, 02:42 AM
"9.8 Newtons"--> wrong

9.8 Newton..... (Do not use plural on names!!)

"KN/m2" ---> wrong

KN=Kelvin Newton, kN=KiloNewton

JohnS
07-17-2010, 08:47 AM
1kg gives 9.8 Newtons. Most people just multiply weight (in kg) by 10 to get newtons.

True, and probably the reason the dekanewton (daN) keeps popping up in questions here.

Unregistered
07-29-2011, 12:03 AM
Hi,

I am still puzzled on how the specs of floor loading works.
Hope that someone can enlighten me.

For Example:

If a floor loading of 1.5kn/m2 is set for a office building,
this would mean that 150kg/m2 is the maximum weight that the floor can withstand.

If we have 4 people weighing 60kg each standing in a m2 on this floor,
it will be 240kg/m2. Wouldn't this cause the floor to collaspe?
(Doesn't sound logical to me)

Thanks
Xder

JohnS
07-29-2011, 03:41 AM
Hi,

I am still puzzled on how the specs of floor loading works.
Hope that someone can enlighten me.

For Example:

If a floor loading of 1.5kn/m2 is set for a office building,
this would mean that 150kg/m2 is the maximum weight that the floor can withstand.

If we have 4 people weighing 60kg each standing in a m2 on this floor,
it will be 240kg/m2. Wouldn't this cause the floor to collaspe?
(Doesn't sound logical to me)

Thanks
Xder

If the entire room were filled with people at a density of 4/mē, it might. The figure is intended to be an average over the entire floor area (but must be reasonably equally distributed). You can't multiply by the area of the room, and then put the entire load dead center. But if the load were spread out in a number of piles with open space around them, you'd be ok.

It is possible to do detailed structural analysis of the floor support and calculate floor loading other ways, but usually you just find this simple uniform load model. The real questions are how the loads are transferred to the floor joists, and how those joists are supported from below. The flooring is run across the joists and tends to spread spot lots over a few joists. The flooring surface will bear and spread out much higher spot loads (one of the worst is women's high heels)

03-06-2012, 03:22 PM
Can I know what is KN/m2.

JohnS
03-06-2012, 03:29 PM
Can I know what is KN/m2.

It should be kN/mē (case is important in SI), kilonewtons per square meter. It is a pressure (could be written kilopascal) or floor loading in terms of force per unit area.

Unregistered
04-13-2012, 08:00 AM
It's a unit of pressure, force per area. For a weight such as a house it would be how much weight over a specific area.

kN = kilonewton, a unit of force.
m2 = mē = square meter, a unit of area

kN/mē = kilonewton/square meter

You can convert kilonewtons to pounds-force or kilograms-force, if that will make it easier to understand.

I Have a Coldroom that will take: 3.09kN/m2 what is that in Kilo's?

JohnS
04-13-2012, 11:58 AM
I Have a Coldroom that will take: 3.09kN/m2 what is that in Kilo's?

Assuming the only forces are gravity acting on masses, about 315 kg/mē
(divide by 9.81 N/kg, the acceleration of gravity)

Raphael Kandalaft
05-07-2012, 01:19 PM
It's a unit of pressure, force per area. For a weight such as a house it would be how much weight over a specific area.

kN = kilonewton, a unit of force.
m2 = mē = square meter, a unit of area

kN/mē = kilonewton/square meter

You can convert kilonewtons to pounds-force or kilograms-force, if that will make it easier to understand.

Iwant to convert KN/m2 to Kg/m2

JohnS
05-07-2012, 04:42 PM
Iwant to convert KN/m2 to Kg/m2

Divide by the acceleration due to gravity (preferably local gravity, but standard gravity 9.80665 N/kg is often used)

1 kN/mē = 1000 N/mē x 1 kg/9.80665 N = 102 kgf/mē approx
(the use of kilogram-force is deprecated)

Unregistered
05-12-2012, 11:14 PM
i am a second year civil engineering student and i am trying to calculate the dead load on a slab with 3.5 kN/m2. The length of the floor is 8850mm and the thickness of the slab is 450mm, now i cant figure on how to do that , can someone give me some tips?
Thank you

JohnS
05-13-2012, 04:16 AM
i am a second year civil engineering student and i am trying to calculate the dead load on a slab with 3.5 kN/m2. The length of the floor is 8850mm and the thickness of the slab is 450mm, now i cant figure on how to do that , can someone give me some tips?
Thank you

You need the width of the slab. Determine area (length times width) in square meters, multiply by the load rating.

What exactly are you trying to determine? The floor load rating is what it can support in addition to its own weight. However the beams must support both the floor and the rated load.

Unregistered
12-13-2012, 01:41 AM
I remember this is junior cert question which is simple Physics, that quy with 1N=9.8kg should really consider about that....