Physics 5 The Universe with Prof

Physics 5 The Universe with Prof. D. Tytler

ANSWERS to Homework 2

Draw a diagram illustrating the phases for Jupiter’s moon Io. You may wish to give two diagrams, one showing the view from far above the orbit, and the other, the phases seen from Jupiter. The goal of this question is revision of the concept of phases.

The key here is the last sentence. This Q is about phases in general. Io is nearly identical to our Moon. This Q is amongst the best ways of checking whether you understand the concept of phases. The answer should be immediately obvious once you understand phases.

These diagrams should look just like diagrams for our moon & it’s phases

(see text fig. 3-3), except for the labels and the times.

Io’s period is only 1.77 days. So, the time between each of the quarter phases (1^st, full, 3^rd, new) is about 0.45 Earth days.

There are 2 types of day and month. Name them & explain the difference. The goal is again revision.

This question is about the definition of the DAY and MONTH. Two types of both day and month: sidereal & synodic.

The former is measured an Earth rotation with respect to the stars, the latter a rotation with respect to the Sun. For the month a lunar revolution is the key motion. See text box 2-4 and fig. 3-5. Know which is longer, and why. You’re really doing well if you can calculate the time difference between them, but this is beyond what is required in this class.

There are 2 types of eclipse, distinguished by the object doing the eclipsing.

Name them.

These are the solar and lunar eclipse, illustrated in your text in figs. 3-8 and 3-12.

Why are eclipses not seen each month? The goal is revision of an important spatial concept.

They are not seen monthly due to the inclination of our moon’s orbit; see text p57.

Of the above 2 primary eclipse types, one is seen much less often, though it occurs more frequently. Explain, using sketches. The goal here is to draw realistic sketches, which will check whether you understand the formation of eclipses.

Solar eclipses occur more often, but since the area of Earth able to witness the eclipse is small, fewer see it. Lunar eclipses occur less often, but half the globe can see them (weather permitting). See text pg. 60-62. Sketches must explain this situation, and no single one in text does alone – there is a need to synthesize.

Summarize the historical development of planetary orbit theory and observations. Chapter 4 of your text has more than enough. Please use one paragraph for each person, and complete sentences. You should NOT copy text from the book.

There is, of course, no single way to do this. If you followed the above criteria and demonstrated understanding of what you wrote you should do well.

Explain the difference between a hypothesis and a theory. The goal of this and the next question is to encourage you to read selected parts of the textbook. Most books will cover these topics.

Page 4 of your text has the definitions in hard-to-miss boldface. Copying them verbatim is acceptable, provided you say that you copied, but you must explain the difference in your own words.

Explain "the scientific method".

Also easily found on pg 4.

Go to http://www.whfreeman.com/universe/con_index.htm?01 . You can get there from our home page, http://casswww.ucsd.edu/ph5/index.html by selecting "links" then "The Universe". This page lists the objectives for chapter 1 of the textbook. We covered most of these topics, but not all. Please make a list of the topics we did not cover, for chapters 1-4. You should be able to do this using the list alone, without looking at the book, although it will be easier if you have a copy of the book to examine. The goal of this question is to help you with revision: to revise efficiently, you must know what we did, and what we did not cover.