To determine an athlete's body fat, she is weighed first in air and then again while she's completely underwater. It is found that she weighs 690 N when weighed in air and 46.0 N when weighed underwater. What is her average density? Express your answer to three significant figures and include the appropriate units.

How are positive ions different from neutral atoms

Which of the following is part of the explanation or description of electromagnetic waves? (select all that apply) a. electrically charged molecules in a medium transfer their energy to nearby electrically charged molecules. b. a changing electric field causes a changing magnetic field. c. magnetic molecules in a medium transfer their energy to nearby magnetic molecules. d. a changing magnetic field causes a changing electric field.

Calculate the numbers of photons having a wavelength of 10.0 mm required to produce 1.0 kj of energycalculate the numbers of photons having a wavelength of 10.0 mm required to produce 1.0 kj of energy