Final answer:
The reading w2 on a scale during hydrostatic weighing reflects the submerged weight of an individual, which is used to calculate body density and estimate body fat percentage.
Step-by-step explanation:
The question provided appears to be related to the concept of hydrostatic weighing, which is used to determine body density and subsequently calculate percent body fat. This is a standard method for measuring body composition and involves weighing a person in air and then while fully submerged in water.
Given that the water displaced will be equal to the weight of the individual in water, the reading, w2, will reflect their submerged weight, from which we need to make corrections for residual air and the metal weight.
This reading can be further used, along with measurements taken while out of the water and possibly skinfold measurements, to determine the subject's body fat percentage.