Why is weight measured in newtons

Credit: NASA. So a trip to space might be a quick way to lose weight, but losing mass is another matter. Jake Port Jake Port contributes to the Cosmos explainer series. More from:. Jake Port. Read science facts, not fiction Read more at Apparent Weight. But in orbit it would not push on the scales at all.

The scales would show On the Moon the scales would wrongly show So the scales show an estimate of your mass based on the force your body exerts on it. The unit for weight is the Newton same as for any other force.

OK, fine—the stupid pound is also a unit for weight. Most humans on the surface of the Earth can get away with saying either "weight" or "mass" because they are proportional to each other. If you know the mass of something m , then the weight W can be found as:. In this expression, g is the local gravitational field. The key word here is "local. It doesn't work at least not very well for kilometers above the surface of the Earth and it doesn't work on Mars. Only on the surface of the Earth is there a proportionality constant of 9.

Since most humans live on the surface of the Earth, no one really complains about using "weight" and "mass" to basically mean the same thing. So, you want to find the mass of that stack of sticky notes? Simple, just put it on a scale and record the reading on the display. Like this. That looks simple, right? It just gives you the mass. But hold on—this scale actually gives you the weight and then does a calculation to get the mass assuming you are on Earth. If you take this scale to Mars, it will not give you the correct mass because there is a different gravitational field.

Actually, this scale does something very similar to this basic spring scale. It measures the force applied to it and then converts to a mass.

But wait! Sometimes this doesn't even give you the weight. What if the scale is accelerating UP? Mass is measured in kilograms. The mass of a given object is the same everywhere, but its weight can change. We use balances to measure weights and masses.

Weight is the result of gravity. This means an object with a mass of 1 kg would be attracted towards the centre of Earth by a force of 10 N.