Please ignore my first paragraph in the last post. JS1138 is right on the freefall determination of mass. The method I described still requires a known acceleration to work. Sorry about that. Second paragraph is still accurate.
Thanks for the clarification.
But the argument started over a claim that immersion was used to measure weight, mass, and body fat. My first response — still correct after all these years — was that immersion measures volume.
You can measure the weight of an object by calculating the weight of the water displaced by a floating object, but as a practical matter it makes no sense to do this with human bodies.
The medical procedure for determining body fat uses displacement to measure body volume. Volume is an essential factor in the equation. Tpanther has consistently denied that volume is of any interest and he/she is wrong. Simple as that.
Even if you use displacement to measure weight, as with ships, you are measuring volume and calculating weight.
Yes, gravity is equivalent to acceleration, and acceleration requires energy, and energy is interchangeable with mass. Therefore gravity is material, even if we still lack a complete description of its attributes.