Assignments

Purpose of Assignments (In Order of Importance)

• They are an extension of instruction: they represent applications of principles covered in class to astrophysical systems.
• They venture into areas related to this course, but not covered explicitly in the lectures.
• They offer practice in solving problems. As such, they constitute preparation for exams.
• They earn you credit towards the final grade for the course.

General Rules and Regulations

• To receive credit for an assignment, it must be turned in on time. There are no extensions to the deadline for problem sets since solutions are distributed at the deadline, nor can problem sets be made up.
• While working on problem sets, you can exchange ideas with your classmates (brainstorm/strategize). However, you should figure out the details and write out the solutions on your own. See also the section of the syllabus on assessed work.
• For group assignments, you will be asked to work with a team. For those assignments, each of you must turn in the team’s answer on Canvas; that is, the grader will grade one set of answers per team, and the team members will get the same score.

Distribution of Assignmens and Submission of Answers

Assignments will be distributed electronically through Canvas. The due date will be announced with the assignment. Typically, you will have one (initial deadline) + two (final deadline) week(s) for the problem sets.

The written responses to all assignments should be submitted through Canvas as single, self-contained PDF files (one file per assignment). It is the responsibility of the students to make sure that the files they upload are readable and can be manipulated by Canvas without problems.

How to Approach Problem Sets and Present Their Solutions

To get full credit for your solutions to problem sets, you must follow the instructions below.

• Always solve problems algebraically (without inserting numbers) to the maximum extent possible. Derive final formulae and insert numbers only at the very end. There are many good reasons for this:
  • It is very instructive and it allows you you to see how different physical effects come into play in the problem (this is a major goal of this course).
  • It reduces number crunching (which is more prone to error and more difficult to check).
  • It is easier to grade and increases the probability of earning partial credit, if you do not solve the problem correctly.
• Carry the units around in all your numerical calculations. They provide a sanity check and can help you spot mistakes. And do not forget to attach units on your final answers.
• Always present the solutions to integrals and differential equations that you encounter. If you do not know how to solve them, you can look up the solution and reproduce it; do not just quote an answer. The only exception are integrals that are discussed and solved in class and/or whose analytic solutions are known to be long and tedious or known not to exist .
• Your solutions should be complete, clear, well organized, and neat:
  • Write neatly and spread out the text and equations.
  • Write text to explain your logic and the steps of the calculation.
  • Show all the details of your work. Do not skip any steps.
  • You are likely to loose points if your solutions are difficult to understand, if they are missing essential elements or steps, or if you do not express the answers in the appropriate form, format, or convention. Therefore, it always pays to read the problem carefully and follow the instructions therein.
  • Use proper, conventional scientific notation.
• The answers for each problem set should be submitted as a single, self-contained PDF file; they can be written by hand and then scanned or photographed (e.g., using Microsoft Lens or Adobe Scan), or they can be written on a tablet and exported to PDF, or they can be typed (or they can be produced by some other method that creates a PDF file). A PDF resolution of 200–300 dpi (dots per inch) is preferred because it results in readable text and files that are not too big to be unwieldy.

General Advice

• Start working on assignments early! Some of the problems require a lot of thought and/or consultation with the instructor (by design). Be ready to come to office hours with your questions. If you wait until the day before the assignment is due you will not have enough time to do a good job and you will not have enough time to ask for help.
• Study the lecture material carefully before attempting the problems. Attempting the problems “cold” is inefficient and defeats the purpose of the problem sets.
• Read questions carefully and understand what you are asked to do. Then, answer the questions completely (do not leave parts out).
• Think critically about the answers you get at every step and ask yourselves if they make sense. This is a very important part of the exercise because (a) it helps you catch mistakes that are sometimes subtle and (b) it forces you to take a step back and look at the solution critically and test your general understanding of what is going on.
• When carrying out numerical calculations keep at least 4 significant figures until you get a final answer. This improves the accuracy of your calculation and protects you from round-off errors and other numerical traps. You can truncate the number at the end, if you think you do not need to report that many significant figures.
• When you get the official solutions for the problem sets, study them carefully even if you got the answer right. They may show you a different way of approaching the problem that what you came up with and they may add to your understanding of the physical system that is the topic of the problem.