Sunday, February 28, 2010
More Hints for HW 2
I have received more questions and comments about HW 2 and decided to post the responses on-line so that you all have some hints on HW 2 (and on what to expect in later HW and the exams). Please let me know if you have other questions about HW 2.
In problem 3.6, what is our starting point? We could start this at m - M(Sun) = -2.5 * log(F/F(10,sun) and have it be pointless.
While the solution is very short, it is not that short. I amguessing that you are assuming you can start with equation (3.4). If
so, you are mistakenly trying to interchange an absolute magnitude M
for an apparent magnitude m. As a hint, I would suggest that you try
to find an equation that includes both m and M in that section of the
book.
What is the advantage of using the rectangle method when we could just use a calculator or Mathematica to get a quicker, more accurate answer?
I'm sure you're used to dealing with simple functions that are easilydefined by an equation. As I mentioned in class, not all functions
(including this one) can be integrated analytically and must be done
numerically. As you will discover later, not all functions can even
be put into the form of an equation! Thus, it is impossible to
integrate them analytically and extremely difficult to integrate them
with Mathematica. However, Excel will handle these problems deftly.
If you desire to use Mathematica to solve these relatively simple
homework problems, please feel free to do so. However, you will be at
a sore handicap in your later research (and possibly on the exams)
when a problem comes up that is nearly impossible with Mathematica but
is trivial with Excel.
While this probably sounds "preachy", my goal in the class is not for
you to solve the astrophysics end-of-chapter problems. My goal is for
you to learn to solve problems using a set of very useful tools. I am
trying to stretch your "Excel muscles" a bit so you are ready for PHY
397/398 next semester.
# posted by Tony Crider @ 3:27 PM 
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