ISP205 VISIONS OF THE UNIVERSE
Section 3, Spring 97, Hufnagel & Stein

FREQUENTLY-ASKED QUESTIONS (FAQ)


WHERE IS THE FINAL EXAM BEING HELD?

Again, there seems to be confusion about the location of the exam. Is it in Natural Science or is it in Wells? I heard both. Thanks for the help.

The final exam for this section is in Natural Science Room 128. The test is 60 questions long, and will run from 8-10pm.

HOW ARE SIZE AND MASS FOR ASTRONOMICAL OBJECTS RELATED?

I am preparing for the final and I have a question. When going over my previous test I was wondering about the question:
Arrange the following  astronomical bodies in order of decreasing size...
and the right answer is:
red giant, sun, earth, neutron star, black hole.
I was boggled by the answer....I thought that black holes are most massive?

The right answer is indeed surprising. Here's why it's right.

Lined up by mass, with highest mass first, the answer is
black hole, neutron star, Sun, red giant, Earth
(assuming that the red giant was the same mass as the Sun when the red giant was on the main sequence.

The reason for the small size IS the large mass, strangely enough. When a star forms, gravity attempts to crush all of the mass into a tiny space immediately. The higher the mass, the higher the gravity, and the smaller the resulting remnant. However, the conditions of high density and high temperature as the star collapse result in fusion and the familiar "balance conditions" that keep the star stable. When the star runs out of fuel, though, gravity can no longer be stopped. The more mass there is, the more the force of gravity and the more the material is crushed together. So that's why the most massive stars form black holes, the next most massive neutron stars, and stars of one solar mass white dwarfs.

The planets have such a tiny bit of mass (compared to the stars) that gravity doesn't crush the material enough to even start fusion. When the Earth finally loses all of its primordial heat, it will only be a little smaller than it is now.

HOMEWORK 10: AGE OF THE UNIVERSE

I have a question regarding the homework problem that asks us to find the age of the universe. I started by converting light years to km/sec but I don't think I used the right conversion (300,000 km/sec to one light year?) and I don't know what to do next. Could you possible email me some "helpful hints"?

The hint is: a light-year is not a unit of velocity. The glossary of your book has a definition of a light-year you will find useful for this problem.

I HAVE BEEN TRYING TO DO HOMEWORK 10 FOR 3 DAYS, AND STILL CAN'T LOG INTO THE DEEP IMAGE. WHAT DO I DO NOW?

This question was structured so you don't need to look at the Image, but only the Table linked to the Image. I didn't have any trouble getting to the Table, which is the URL given in the the homework, and linked to the Homework 10 on the Web.

The last column of the table gives you a galaxy type, which is explained at the heading of the table. If it doesn't have a type, it can't be classified...which tells you something important!

WHEN DO WE CHOOSE WHETHER TO GO TO THE PLANETARIUM OR THE FINAL EXAM REVIEW ON THE 24TH?

The syllabus says that for the last day of class we will be choosing to go either to the Planetarium or to have a review session for the final exam. When will we know which is the one to go to?

Both events will be happening simultaneously. If you think you will be taking the final exam, we recommend that you attend the review session in PA Room 118, the usual classroom. If you are not taking the final exam, we recommend that you go to the Planetarium. If you have taken all three midterm exams and are satisfied with your grade, you need not take the final exam.

WHERE CAN I OBSERVE COMET HALE-BOPP FROM?

Beginning Monday (March 24) and continuing at least through Sunday (March 30), and possibly longer if interest warrants, volunteers at the MSU Observatory will show the Hale-Bopp comet to those who stop by between 7:30pm and 8:30pm.

Note, however, that in some ways the MSU Observatory site is not the ideal location for seeing the comet, because the northwest view (the direction in which the comet will be seen) is toward the lights of the city of Lansing. You might want to head for a darker location away from city lights to get a view of the comet, particularly if you have binoculars. Right now the comet is so bright that there is no problem with its identification once evening twilight begins to descend.

THE FROZEN BALLOON EXPERIMENT

It seems clear why the balloon deflated when it was frozen, but what was making it inflate itself again?

The balloon deflated because the air inside the balloon was cooled off. This slowed down the particles inside, and therefore they stopped hitting the inside of the balloon and the pressure inside dropped. The balloon then shrank. Yes, the molecules inside did stop moving so much, but they were all still there

Then, when the balloon gradually heated up again, the molecules inside started moving faster, hitting the sides of the balloon much more often and harder (i.e., increased the pressure), and inflated it again.

This is the same phenomenon that requires you to check the air pressure on your car tires when they're cold, not after you've been driving and the tires are hot. Also, you can't take the lid off a pressure cooker when it's boiling as it will explode BUT you didn't add any water, just heat. The same number of water molecules have much more pressure as steam than as liquid water.

THE FINAL EXAM

Are we required to take the final exam? Also, will it be cumulative?

Your final grade will be the average of your home and in-class work plus the best three of your test scores. If you have taken all three midterms and are satisfied with your grade, you need not take the final. Usually, about half of the class takes advantage of this option. If you do take all four tests, we will automatically use the highest three to compute your grade.

The Final will cover all three sections.

Also, please note that the date of the second midterm has been moved from March 27th to April 1 (no joke!).

STUDYING THE STARMAPS

The starmaps in the book look different than those you give us in class. Are there blanks we can study from?

We are in the process of scanning in the maps to have them available from the Internet, but this isn't ready yet. For this first midterm, we have a number of blank sets of 12 starmaps similar to what you will be getting on the midterms and finals. If you would like one, please ask for a set of the star maps either before or after the review class on Tuesday.

HOMEWORK 3, QUESTION 6 LIST TWO TESTS OF COPERNICUS' MODEL

What do you mean when you use the term "tests?" Is this one of those words that means something special in science?

By tests we mean a prediction of the Copernican theory, such as a consequence of the movement of the Earth, that could be compared with some observation to see if it really occurs. Based on ancient physics a consequence of the Earth moving would be to leave the Moon behind and clearly that does not happen. Hence, either the physics on which this prediction is based is wrong (true) or the Copernican theory is wrong.

Actually, the Copernican and Ptolemaic theories predictions of the locations of the planets were of the same accuracy. That the Copernican model needed a large number of epicycles to explain the details of planetary motion would be a argument against it on aesthetic grounds -- we prefer simple to complex theories -- but is not an argument against it on whether it agrees with observations or not (tests).

What you need to do is go over your notes (and look at the outline on the the web) to find the discussion of tests of the Copernican and Ptolemaic and Keplerian models. You may have to figure this out for yourself, rather than just finding the answer and copying it. The relevant section in the text is Chapter 2, section 2. The meaning of "tests" in this sense is not very different than everyday English, as in "I need to test this battery."

WHAT SHOULD I BE STUDYING FOR THE FIRST QUIZ?

Our first quiz is coming up on Thursday evening. I've attended all classes and labs and accessed the Web Page. I have learned a lot already and it is interesting for me, but what should I be studying for this quiz?

The topics we are stressing are the ones covered in homework, in-class activities, and in class. In addition, you should know the 16 brightest stars and how to locate them in the sky. (This will be on every midterm and the final.) We are not going to pull topics from your textbook which did not appear in any of these 3 media. We also will not include material only presented in the labs, as this is a separate course.

The quiz is an exercise (with credit) designed as a "warm-up" for the midterm. The format is the same as homeworks and the midterms: a mix of short answers, multiple-choice, and drawings.

FINDING INFORMATION ON MARS

How do I find links to information on Mars, Meteorites from Mars and Life on Mars?

Look at the bottom of the the isp205/sec-3 home page where there is a section entitles: "LINKS to ASTRONOMY RESOURCES". Under that is a link called "Life on Mars". Click on that to follow the link and you will come to the "FAS Space Policy Project" page with links to many different types of information about life on Mars and meteorites from Mars. Some items are for general public consumption, some for students and some highly technical for experts. Hunt around and find some sources that satisfy you.


This page will be continually updated as the course progresses.
{ Updated: 1997.04.29 (Tuesday) 08:32:09 EDT }

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Beth Hufnagel's home page, email: hufnage4@pilot.msu.edu
Bob Stein's home page , email: steinr@pilot.msu.edu