If gravity varies round the Earth, how do the inspectors of weights and measures arrive at standard weight?

Question

For instance, if the inspectors of weights and measures determine what 1 lb weighs, if the gravitational pull of Earth varies, the weight of their 1 lb will vary too and a standard cannot be reached. So how do customers get their pound of corn, for example?

Answer 1

To Weigh something is nothing to do with weight, which varies with gravitational pull of earth. When you go for buying something and demand 1 lb of corn, you are, in fact, demanding 1 lb MASS of corn, not WEIGHT of corn.

MASS is the property of an object that is a measure of its inertia and the amount of matter it contains.

Whereas WEIGHT is the measurement of MASS multiplied by the GRAVITATIONAL PULL CONSTANT.

w = mg

So we can say that weight depends on the mass of a body, but mass is not dependent on weight.

So when you say "Please give me 1 kg of Sugar?" You are demanding quantity of Sugar which has a mass of 1 kg.

I hope this explanation will satisfy you.

Answer 2

If you use precise scientific instruments you can detect changes in the Earth's gravational pull. For everyday people the amount of change is so insignificant as to be unimportant.

Answer 3

i think a standard scale set to true zero in the area of it's use would go up in true increments of 1lb and so forth. i could be wrong.