This is regarding a digital bathroom scale; idk if it happens on analog ones, too. I’ve noticed that shifting my weight to one foot, to the balls of my feet vs my heels, etc. changes the weight readout–sometimes up to two pounds’ difference! So I’m curious to know why changing the weight distribution even a tiny bit affects the readout so drastically, when the same amount of weight is still on the scale.
In: 25
The scale is measuring how much force you are putting in it. If you don’t stand in the middle of it (or rather with your weight pushing straight down) it will misread the force, because it’ll only register the straight downward component.
Depending on how exactly the scale is set up, this will lead to different errors.
Take for example a scale with 4 force sensors in the corners, if you just stand on one side of it, even worse on the outside of those sensors, you will twist the other side of the scale up, reducing the force in those sensors, while also not pushing straight down on the sensors if your side.
This is why highly accurate scales have an integrated water level: you need to adjust the feet of the scale to be perfectly level, so the force whatever you are weighing is putting down towards the center of earth is in exactly the same direction.
For human scales it really doesn’t matter, as a pound or two is well within daily fluctuations of body weight from food/drink/poop/urine.
You’d only need to make it perfect if you were doing some research where grams matter.
Which you could solve, if you were using a platform suspended on a string to a single force sensor it wouldn’t matter where in the platform you stand though, unless currently swinging around with the whole platform.
Latest Answers