Intro Physics Since this is a Physics Forum, our theme this week is related to that subject area. In Intro Physics classes, we often use various examples to illustrate the basic physics principles. This includes the simple pendulum, Hooke's Law spring, projectile motion, mass on an inclined plane, uniform circular motion, ballistic pendulum, roller coaster, etc. Your task is to show a photo of a TYPICAL example or problem that is often used in intro physics classes. For example, a picture of a trebuchet will qualify as an example of projectile motion. If you think your example is typical, but may be obscure, you may have to include a brief explanation. Good luck! Zz. Contest Rules: 1. Any digital photo or digitally-scanned photo relevant to the theme will be accepted within the contest period. In case there's a gray area, or you're not sure if the picture is suitable, check with me first. 2. Please resize your digital photo to no more than 800 x 600 or 600 x 800 pixels. You may also crop your picture if you wish. You are also allowed to adjust the brightness and contrast of your picture but these should not dramatically alter the look of the picture. But other than those, any form of picture editing or modification is not allowed. This is a photo contest, not a picture editing/special effect contest. You may add a watermark or your name/nickname to the photo for identification purposes. 3. Upload your photos to any of the photo servers such as imageshack or photobucket. Then post it the relevant contest thread and link your picture using the img command. PM me if you do not know how. 4. Only ONE picture per member per contest. Once a picture is posted, it cannot be changed other than a total withdrawl by that member from that week's photo contest. Exceptions will be made for modification to comply with the rules, such as resizing. 5. At the end of the contest period, I will open a poll and every PF member can vote for the picture they like best. 6. Note that in case we have a large number of entries, I will do the polling in more than one thread. If that's the case, you can vote in each of the polling threads. The photos will be assigned in the polling threads in the order they were submitted. 7. The photo of the subject must be something that you took directly, not via in intermediary medium, and not taken by someone else. Unless otherwise noted, a photo of another photo, painting, print, etc. does not qualify. 8. You can use a picture only once. Once it is used in a contest, it cannot be reused in another contest. 9. Please post only pictures meant for submission in this thread. Photos not meant for submission must not be posted in the contest thread. Posting of more than one photos by a member may result in an automatic disqualification from the week's contest. Zz.