A student determines the average speed of a bubble rising through a liquidat constant speed When the student starts the stopwatch the bubble is at position P.
After 20s the bubble is at position Q.
bubble
18
19
20
21
22
23
24
25
OP
.
26
cm
27
bubble
What is the speed of the bubble between P and Q?
A 32 cm/s
B 3.7 cm/s
C 6.4 cm/s
D 7.4cmis

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.