At a playground a student runs at a speed of 5 m/s and jump onto a circular disk of radius 32m that is free to rotate around a fixed vertical axle. The student jumps on the disk several times, and the angular speed after the student lands is measured each time. Which of the following angular speeds is not a reasonable value for the measured angular speed? a. 0.5 rad/s
b. 1 rad/s
c. 2 rad/s
d. 3 rad/s
e. 4 rad/s

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.