HOMEWORK ASSIGNMENTS:
Problem assignments will be posted weekly and you have 1 week to complete them (with the exception of the first assignment). Assignments will be collected at the end of class on Friday. Late assignments will be accepted, but some points will be taken off. You may redo some HW assignments if I find it beneficial, but some points will be taken off.
Here are some tips borrowed from Dr. Richard Sonnenfield:
Identfy -
- In fact, as more experienced physicists, I would replace the word “identify”, with the word “insight”. What is the key insight required to solve (or simplify) the problem? Are you going to use conservation of energy? Are you going to choose a non-inertial reference frame? Are you going to solve the problem with reference to the center of mass of the system? Is there something even sneakier that you need to do. Once you've decided, explain your approach.
Setup -
- A picture of the system should always be drawn. The picture should be clearly readable (meaning also not too small!). Perhaps forces should be indicated on the picture. Almost certainly your choice of origin should be indicated. The coordinate axes should be labeled and the direction in which they are positive labeled (or you could draw x, y and indicate that you are using a right-handed (or left handed!) coordinate system. The variables you will use should be identified, listed and defined. The key formulae required should be listed in generic form, then specialized to the problem at hand. Often certain terms in a formula may be ignored, or set to zero, or to constants. You should do this, and if it isn’t obvious why it’s OK to do this, you should explain it in a sentence. As we move into the Lagrangian method, a key element to the solution is the correct choice of “generalized” coordinates. You should indicate why you chose the coordinates that you did.
Execute -
- This is the number crunching step. Show ALL your work. Keep it orderly. If I can’t read it EASILY, I will give it back to you. Use the English language where needed (e.g. “regrouping”, “canceling like terms”, “multiplying both sides by 1”). If your handwriting is fundamentally messy (some of us have this curse), you need to compensate (as I do) by leaving plenty of WHITE SPACE so I can read your formulae more easily. Your final answer should be enclosed in a box. When you have nearly finished the problem, you may find that it is rather illegible. Often the “Insight” step is not really complete until you have worked all the way through, or nearly so. You may need to rewrite the problem for clarity of presentation after having solved it once in a rough way.
Evaluate -
- Check that your answer is reasonable. Often this is done by reducing a complex formula to a simpler case in which the solution is more obvious. Check that your result DOES simplify in a sensible way. Sometimes an order of magnitude estimate is useful. Sometimes an alternate approach is available. (Often a conservation method may be used instead of a force method to get a solution that is the same, or approximately the same).