What is a phase?
Q: What is a phase?
A: A phase is one part of a cycle or change that goes in a circle.
Q: Can you give an example of something that has phases?
A: The moon, the seasons of the year, and Venus all have phases.
Q: How did Galileo use the phases of Venus to prove something about its orbit?
A: Galileo showed that the phases of Venus meant it must go around the Sun, not the earth.
Q: What can be used to represent things with phases?
A: Graphs can be used to represent things with phases.
Q: How do things with phases change over time?
A: Things that have phases change in some regular way from time to time.
Q: Can two pendulums move together if they are different lengths?
A: No, unless they begin swinging at the same time and place they will not move together. One may be swinging left while the other swings right. When this happens, they are "not in phase."
