Homework Assignment #8
This assignment is due at the beginning of class on Friday, November 14. Late homework absolutely will not be accepted, including homework turned in at the end of class. If you can't make it to the beginning of class, make sure to turn your homework in to me beforehand.
You must do the first three problems. Each of those problems will be worth 10 points. If you make a sincere, honest effort to answer each question, you will receive at least 5 points of credit.
Staple your homework! If you require more than one page to complete the homework, fasten the multiple pages together with a staple; folding the corner won't cut it. If your homework has multiple pages but you fail to staple, you will be docked 3 points.
The last two problems are given to you as additional review problems. You do not need to turn them in, and they will not be graded when you do. However, solutions to them will be posted along with the solutions to the first three problems. You may want to do them if you think you need extra review in the class.
Please write out the problem statement at the top of your solution. (This is for two reasons; it is so I can know which problem you answered, and that you answered the right problem from the book. It also will make your graded homework more useful as a study aid later.)
Chapter 13, Question 12 (page 351).
Right now the Sun is a main-sequence star. Later in its life, it will become a red giant: it's luminosity will go up hundreds or thousands of times, it will be many (between ten and a hundred) times larger, and it will be a bit cooler.
- (a)Will the rate at which the Sun converts some of its mass to energy be higher or lower when it is a red giant as compared to now? Why?
- (b)Do you expect that the pressure near the surface, but inside the Sun, will be higher when the Sun is a red giant than it is now? Why?
- (c)Do you expect the solar wind to be more intense (i.e. more particles coming off of the Sun per second) when it is a red giant or now?
Consider a two large clouds of gas with solar abundances (i.e. mostly Hydrogen and Helium, with just a little bit of other things mixed in). Take one cloud of this gas, and make sun-like stars out of it. Let the sun-like stars live their main sequence lifetimes, and then (somehow, magically) disperse those sun like stars back into a cloud of gas. Qualitatively, how will the relative elemental abundances in the cloud which was processed through sun-like stars compare to the cloud which just remained a large, quiet cloud of gas?
(The problems below will not be graded, and need not be turned in.)
Chapter 15, Question 14 (page 399).
Chapter 16, Question 11 (page 431).