On a small planet, an astronaut uses a vertical
force of 175 newtons to lift an 87.5-kilogram
boulder at constant velocity to a height of
0.350 meter above the planet’s surface. what is
the magnitude of the gravitational field strength
on the surface of the planet?
(1) 0.500 n/kg (3) 9.81 n/kg
(2) 2.00 n/kg (4) 61.3 n/kg

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.