To all smart men out there, please answer this.?

Question

If the weighing scale measures the weight, why is it expressed in kilograms instead of Newton?

Answer 1

You are right. Kilogram is the unit of mass in SI, while weight is not mass and should be measured in unit of force, i.e. newtons.

However, prior to the introduction of SI in 1960, physicists used kilogram-force (kgf) as unit of force, hence unit of weight, and today this unit is still preferred to newton in daily life and in some industries. Kilogram force (a non-SI unit) was defined as the force that the earth exerts on an object of mass 1kg at a place where the acceleration due to gravity is 9.80665 m/s². So 1 kgf = 9.80665 N. Approximately, at any place on the earth an object of 1 kilogram mass (kg) weighs roughly 1 kilogram-force (kgf).

Another reason why the weighing scale is graduated in kilogram rather than in newton is that in some case it actually measures mass, not weight. If you use a scale with elastic spring, the deformation of the spring is related to the force acting on it. In that case the scale does measure weight. It will give different readings depending on whether you use it at the equator or at the norh pole. However, if you use a scale with standard weights moving on an arm of the scale to balance your weight, what it really measures is the ratio of your mass and that of the standard mass. It cannot detect your change of weight as you move from equator to north pole.

Answer 2

No wounder you cant get the answer yourself. You seem to think only men can do it.

Answer 3

HAHAHA, darn good question.

Most in the general population have at least heard about kilos, even us dumb Americans, but how many know about newtons? In contrast, how many know "slug" is the unit of mass in the foot-pound-second system (FPS)?

BTW, why did you target men, and smart ones no less?

Edit: I hope you understand I wasn't being critical.

You make a valid point. I don't think there is a device generally available to measure mass directly. Scales have to measure weight, then convert to mass for display.

Also, from Wikipedia:

"The word pound comes from the Latin word pendere, meaning "to weigh". The Latin word libra means "scales, balances" and it also describes a Roman unit similar to the pound-force. This is the origin of the abbreviation "lb" for the pound."

http://en.wikipedia.org/wiki/Pound_(mass...

Answer 4

Anthea,

There is a very simple answer to this question...

Most 'lay-peole'... I mean non-scientific people in this world use the word weight and mass interchangeably.

So when a person askes you... how much do you weigh? what they're really meaning is... how much MASS do you have?...  

Hence, 'weighing-scales' have kg as their results.

If weighing scales were to have Newtons (as in the Newton scales/springs you've used in your Physics lab/prac sessions).. then for normal lay-people to grasp at how much mass they have, they would have to divide their result by ~ 9.8  (and this may be a little too difficult for some...)

And also for the 'ladies'... it's much less embarrassing to say that your 'weight' (mass) is 50 kg... rather than ~ 500 Newtons!!!...he..he..

Answer 5

I am sorry but you will never get an answer asking a question like that..lol. I am joking guys you are all very smart in your own way.

Answer 6

Because a kilogram is the international standard used for weight.  The United States is the only country in the world that uses lbs.  Everyone else uses kilograms.  What does newton have to do with anything?  Newtons are used to determine force.  Weight is not the same thing as force.

Edit: Yes, it is true that weight is related to force.  But think of it this way.  Weight usually deals with gravity.  Force can deal with many things, such as a car crash or a punch from a boxer.  Force also usually includes moving objects.  When you WEIGH something, you are measuring the GRAVITATIONAL force on the object.  So you would measure in kilograms.  Why would you measure in Newtons?

The formula to finding a newton is Force=MassXAcceleration.  Do you know how fast gravity is accelerating?  Nope.  That's why you measure it in kilograms on a scale.  Simple?  Indeed it is.