What does the weighing scale we use in our homes actually measures? As weight should be in Newton and it measures in Kilograms so does it measures our mass ? Why we say that our weight is x Kilograms when we should say the weight is x Newtons , it is too confusing for me .
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First, strictly speaking, kilograms are mass, Newtons are weight (or even more accurately – force. Weight is just one specific kind of force). However, in everyday speech, people use “weight” for both because it’s a similar thing.
Second, many measuring devices don’t measure directly.
Depending on the type of scale, it actually measures the displacement of springs, or current that flows through the circuit (that depends on the load). That measurement is then translated to your mass.
That’s similar to how, with a mercury thermometer, you don’t measure temperature. You measure the length of the mercury line. But whoever made the thermometer knows which length corresponds to which temperature, so the temperature scale is calibrated accordingly.
First, strictly speaking, kilograms are mass, Newtons are weight (or even more accurately – force. Weight is just one specific kind of force). However, in everyday speech, people use “weight” for both because it’s a similar thing.
Second, many measuring devices don’t measure directly.
Depending on the type of scale, it actually measures the displacement of springs, or current that flows through the circuit (that depends on the load). That measurement is then translated to your mass.
That’s similar to how, with a mercury thermometer, you don’t measure temperature. You measure the length of the mercury line. But whoever made the thermometer knows which length corresponds to which temperature, so the temperature scale is calibrated accordingly.
Most modern scales do measure newtons and convert, but still some of the most accurate types directly measure kilograms. And beyond a century ago almost all scales directly measured kilograms or other units of mass.
Check out the [triple beam balance](https://en.wikipedia.org/wiki/Triple_beam_balance) and the [pan balance](https://en.wikipedia.org/wiki/Weighing_scale).
Most modern scales do measure newtons and convert, but still some of the most accurate types directly measure kilograms. And beyond a century ago almost all scales directly measured kilograms or other units of mass.
Check out the [triple beam balance](https://en.wikipedia.org/wiki/Triple_beam_balance) and the [pan balance](https://en.wikipedia.org/wiki/Weighing_scale).
Whenever you have a measuring device you only know what it measures but how it provides you data is at first is a bit unknown. Its some number that contains information about the thing you measure. With a scale you measure weight.
So you place an apple on the scale and it outputs 618. That is the weight but we would like that information to be in a way it makes sense. So we know we weight is measured in Newtons but there is a correlation between mass and weight through gravitational acceleration.
So lets start by turning that 618 into Newtons. We grab weights we know. Lets say we have measure the gravitational acceleration in the lab and now we know that the weight of object 1 is 1N object 2 is 5N and object 3 is 10N. Lets put 1 one the scale and it outputs 629, then 2 giving us 3145 and 3 for 6290.
So when we plot the known weights in Newtons as a function of the scale’s output we get a 3 points that are all on a line in this case, we can say that we got a linear relationship so lets fit a line. y=m×x. x is what the scale outputs and y is the weight in Newtons, m is the conversation factor. Here that would be m = 1/629.
So now when the scale outputs a number we can convert it to a weight in Newtons. That is calibration. If we want to turn that to mass we often take g=9.81m/s² its g around 45° latitude. And lets multiply m with 1/g to give us the conversation factor between the scales output and mass.
If its an analog scale we just make the numbering of the scale in that way if its digital we just output the converted amount.
So you don’t know the connection between the things your measuring equipment outputs and the things you measure, thats what calibration is for to find this connection. After that you can make the equipment outputs anything.
Whenever you have a measuring device you only know what it measures but how it provides you data is at first is a bit unknown. Its some number that contains information about the thing you measure. With a scale you measure weight.
So you place an apple on the scale and it outputs 618. That is the weight but we would like that information to be in a way it makes sense. So we know we weight is measured in Newtons but there is a correlation between mass and weight through gravitational acceleration.
So lets start by turning that 618 into Newtons. We grab weights we know. Lets say we have measure the gravitational acceleration in the lab and now we know that the weight of object 1 is 1N object 2 is 5N and object 3 is 10N. Lets put 1 one the scale and it outputs 629, then 2 giving us 3145 and 3 for 6290.
So when we plot the known weights in Newtons as a function of the scale’s output we get a 3 points that are all on a line in this case, we can say that we got a linear relationship so lets fit a line. y=m×x. x is what the scale outputs and y is the weight in Newtons, m is the conversation factor. Here that would be m = 1/629.
So now when the scale outputs a number we can convert it to a weight in Newtons. That is calibration. If we want to turn that to mass we often take g=9.81m/s² its g around 45° latitude. And lets multiply m with 1/g to give us the conversation factor between the scales output and mass.
If its an analog scale we just make the numbering of the scale in that way if its digital we just output the converted amount.
So you don’t know the connection between the things your measuring equipment outputs and the things you measure, thats what calibration is for to find this connection. After that you can make the equipment outputs anything.
If you’re in an environment where gravity is constant, then weight and mass are basically interchangeable. There’s no real difference between saying an apple has a mass of 0.1kg as saying it weighs 1N when you’re standing still on earth.
The difference becomes apparent when you start to accelerate up or down, or go into orbit, or go do another planet or moon. But for the vast majority of human existence and scientific inquiry, we have been dealing with static objects on earth, so the distinction hasn’t been that important.
You could imagine a future where people have colonised Mars, Earth has been abandoned, and somebody asks on ELI5 why “The Moon” is the name of a moon orbiting a different planet from the one they are on. We are creatures of habit, and it takes effort to change names for things!
If you’re in an environment where gravity is constant, then weight and mass are basically interchangeable. There’s no real difference between saying an apple has a mass of 0.1kg as saying it weighs 1N when you’re standing still on earth.
The difference becomes apparent when you start to accelerate up or down, or go into orbit, or go do another planet or moon. But for the vast majority of human existence and scientific inquiry, we have been dealing with static objects on earth, so the distinction hasn’t been that important.
You could imagine a future where people have colonised Mars, Earth has been abandoned, and somebody asks on ELI5 why “The Moon” is the name of a moon orbiting a different planet from the one they are on. We are creatures of habit, and it takes effort to change names for things!
Bathroom scales measure resistance. The springs can push back up to a certain amount of force, and the dial (or potentiometer in an electronic scale) is connected to the spring in such a way that how much it turns points to what fraction of the max force was applied.
Say a scale is rated for 300 pounds. A person who’s 150 pounds steps on, the spring compresses halfway and then hits the point where it’s pushing upward with the same force as the plate is being pushed down- that’s equilibrium. The dial is calibrated so that halfway is marked “150 lbs,” but what it’s really telling you is how far down the person pushed the plate before the spring started pushing back.
You can have fancier scales with magnetometers instead of a mechanical linkage, but it’s still following the same logic:
* The plate is this far away
* The spring stops up to this much force
* The spring stopped this much of the max force to stop the plate here
* Therefore, this is the weight that was applied to the scale
Bathroom scales measure resistance. The springs can push back up to a certain amount of force, and the dial (or potentiometer in an electronic scale) is connected to the spring in such a way that how much it turns points to what fraction of the max force was applied.
Say a scale is rated for 300 pounds. A person who’s 150 pounds steps on, the spring compresses halfway and then hits the point where it’s pushing upward with the same force as the plate is being pushed down- that’s equilibrium. The dial is calibrated so that halfway is marked “150 lbs,” but what it’s really telling you is how far down the person pushed the plate before the spring started pushing back.
You can have fancier scales with magnetometers instead of a mechanical linkage, but it’s still following the same logic:
* The plate is this far away
* The spring stops up to this much force
* The spring stopped this much of the max force to stop the plate here
* Therefore, this is the weight that was applied to the scale
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