The acceleration due to gravity on the Earth's
surface is g. If R is the
radius of the Earth, what
is the acceleration due to
gravity at a height 2R above
the Earth?

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.