The Deal with Honors Physics Homework

Philosophy

We will have homework every school night during the year. Completing homework is a critical part of your physics development. A good homework assignment is one where you have to struggle a bit to complete the work. Physics homework is seldom repetitive: each assignment brings new skills and concepts into play. You will be most successful if you make homework a daily routine. Homework is always posted on the calendar by 3 pm. It is due the next day at the beginning of class. Please don’t work on physics HW in your other classes: I want my colleagues to like me. It is OK to get a bit of help from peers or tutors but don’t rely on others too much or you won’t develop problem solving stamina. Mindlessly copying homework from someone else isn’t cheating, but it doesn’t really help you either. The situation is analogous to weight lifting. To build muscle it isn’t enough to watch someone else pump iron: you have to do it!

What does good homework look like?

Good homework shows your work clearly. Do each assignment on a separate 8-1/2” x 11” sheet of paper(s). Often this will mean just printing off the homework like this assignment. Make sure that the HW# is written and boxed on the top right corner. Simply recording the answer to a problem is not worth any points. Keep in mind that every homework problem in physics requires a sketch. Show your work; don’t just write down an answer.

Getting credit for homework

You’ve been good. Where’s the payoff? I will score your HW at the beginning of class. Each assignment is worth 4 points. Genuine effort earns a 4, partial work earns a 2, and insufficient work earns a 0. At the end of the unit on the day of the exam, turn in all of your homework in a single packet. Place the homework assignments in chronological order (HW #1, HW #2, HW #3…numbering forward like the pages in a book.) Put a cover sheet (which you can download from the calendar) on the front of your packet. You get to total your homework packet scores. Never score your own individual HW assignments: that’s my job! Do an honest job of totaling your points or you will risk loss of credit for the entire packet.

What do you do if you have a legitimate excuse for missing a day when homework was scored? Show me your HW on the day you return. Ideally, you should check the web site SaxbyPhysics.com so you can get credit for the homework that is due on the day you return.

Alright, enough talk! Let’s get to your first HW. Ready? Go to page 2…

HW #1

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Suppose you wanted to know about how many stars your naked (unaided) eye could see in the entire sky. Let’s use the same image we used in the PJ. Let’s superimpose 4-20o x 20o squares onto this image. Assume that the tiny circled star just above Altair is near the limit of human vision on a dark night.

A) About how many visible stars do you count in the top left square? Circle them!

B) Estimate how many visible stars are contained in these 4 squares using your count from part A). Don’t try to count all these stars individually!

Altair

20o

20o

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C) Now lets use your count from part A) to estimate the total number of visible stars in the entire sky. 1. Begin by calculating the number of stars per square degree.

2. Now find the number of square degrees in the entire sky. Hint: there are 360o in a circle…use this factor twice! Sketch a sphere with 1 square degree on it.

3. Combine your answers to parts 1 and 2 (paying attention to units) to estimate the total number of visible stars in the entire sky. Assume nothing, not even the Earth itself, is blocking your view and you can see all 360 degrees of sky.

D) Do your think you estimate in part C) is likely to be an overestimate or an underestimate? Why?

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