How do you weigh a person or anything else in space?

Answer 1

Technically, you can't. In space you are virtually weightless, as the gravity is virtually nothing. Weight is the measure of the effects of gravity on a specific mass, and if there is no gravity, there is no weight. Measuring mass, however, is completely different. The fact the there is no gravity makes this difficult, unfortunately. This is because we typically measure mass either a) through calculations from weight to mass or b) through water levels by sinking the item in water and measuring the difference in water levels, which also requires gravity.