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# Why can't a spring scale measure mass?

Updated: 9/22/2023 Wiki User

11y ago

It's quite difficult to directly measure mass. It's relatively easy to measure force, which is what a spring scale does.

(A balance scale measures force also, but it measures the force exerted by a known mass compared to the force exerted by an unknown mass. This corrects for local variations in gravity.)

Spring scales can measure mass by comparing the weight of an unknown amount of material to that of a known mass of material. Hence if you weigh a liter of water (with a constant mass of one kilogram) the scale will show a weight which is dependant on the local attraction of gravity (say about 0.17 kg on the moon). Weighing the unknown will show a weight (again on the moon it would show 0.34 kg) which can be related to the weight of the liter of water and used to determine the mass. In this case, as the weight is double that of the water, the mass would be double that of the water. Wiki User

11y ago   Earn +20 pts  