kg as Force?

[Beggar]

A prospective customer is apparently asking our sales folks for wind load data in kg. In this context, do you suppose they mean kN/g or is it likely to be a typo?

I'm not sure where they are located... somewhere in Asia, I think... perhaps Indonesia.

 

[mirekp]

Maybe they mean the load in kilograms
1kg - 9.8N

Mirekp
Mechanical and engineering calculations

http://www.mitcalc.com

 

[JAE]

Wind load on what? Is this a building or equipment?

For buildings (and most everything), wind is always given in force/area units based on a wind speed.

If you have a fixed type of equipment, with a fixed area and shape...such as a bundle of lights at the top of a pole, then you might have a design wind load in terms of just force. But ultimately, this is based on a force/area quantity.

 

[Beggar]

JAE, this is a fixed system - it's a broadcast antenna.

Apparently the RFQ says "wind load: kg"

 

[JAE]

Sounds like its the total wind force developed by the antenna - Usually the antenna is attached to a tower of some sort which requires the total wind force from the antenna for a design check on the tower.

 

[rmw]

There are some good threads in this site having to do with units, and the explaination of kg as an older unit of force. I dealt with a spanish product that used kg until recently.

You might try searching the sight on several terms associated, e.g. units, kg, m/kg, metric are a few that come to mind that might bring you to these threads.

Some very knowlegable people helped me with this issue, since I was not raised nor educated in a kg system.

rmw

 

[connect2]

kg is a unit of mass in the SI system.
kn is a unit of force in the SI system.
the difference being gravity.

 

[FM1]

This really depends on the part of the world you are working. there are 2 meteric systems, SI and MKS, where in the latter the gravity is factored out and force is stated in KG per unit area which makes for working with smaller numbers. (MKS= meters, KG, Seconds).

 

[FM1]

I just noticed that your client is in asia, in which case they are asking the right question and I wouldnt think it is a typo. Nontheless, you might wanna double check.

 

[Beggar]

FM1, thanks. I recall hearing about MKS at some point but had forgotten all about it and have never seen it used.

Just to be safe, I've given the number in lb and kg just so there's no confusion. If they're expecting kN then they can convert it.

 

[jhardy1]

FM1,

In the MKS system, the kilogram is STILL a unit of mass, not force.

However, I have seen many engineering calculations from Europe (France and Germany in particular) and Japan, which use the kilogram weight as a unit of force.

One kilogram weight is the force acting on a 1 kilogram mass under 1 g of acceleration (approximately 9.807 m/s/s).

 

[sacem1]

When we look at a wind load table in a US written book we find that the units usually used are lbs/sq.ft in the metric world (almost all of the rest of the world) we usually use US books because they are technically good, usually cheaper than locally written or traduced books and more important more UP TO DATE, knowing this as a fact it is not uncommon that we just convert the units to kg/m2 just by dividing the lbs by 2.2 and the multipliying the sq.ft. by (0.305)squared then even if we do not use the kN units we can work with your data easily, I think the answer to the Kg as a force unit still in use is that.

Cheers

SACEM1

 

[FM1]

JulianHardly,
Thanks, I stand corrected. I realized over the weekend that I have stated it incorrectly. But Kg, nevertheless, is used(missused!) as a unit of force, e.g. 300Kg/cm² for concrete strength.

 

[IRstuff]

Sure, just as is the case with pound mass and pound force. In fact, my favorite program defaults to pounds as a unit of mass, and they create a unit "lbf" for pound-force.

So long as the context is clear, there shouldn't be any issue, particularly if your calculations do the dimensional analysis correctly.

TTFN