5-5-09

Daily agenda for the day DQ Video Beats + doppler effect

First we started off with the daily question which was: A standing wave is produced in a tube that is three meters long. The tube has 2 open ends. 1. Draw the standing wave in the 3 meter long tube if the 1st harmonic is sounded. Here is a picture of the 1st harmonic in a 3 m tube with 2 open ends. The second part of the question asked: How long is 1 wavelength? Since the picture about is showing half of a wave, we know that the wavelength is 6m.

After the daily question we watched a video on resonance. The video was a bout a bridge in washing that collapsed due to resonance in 1940. The bridge would sway up and down during smaller amounts of wind and also during larger amounts of wind but was never considered a true threat of safety, but one day when the winds stayed at a constant 42 miles per hour, the bridge started to twist and turn violently. The bridge then collapsed due to this continuous twisting. The bridge only collapsed because it stayed at a constant 42 miles per hour for such an extended period of time.

Next we did an online activity on beats and the doppler effect. We used the website webphysics.davidson.edu/physlet_resources/bu_semester1/index.html and watch the effect on the different frequencies of waves interacting and the products they make. Next we went to the same website clicking on a different link to observe the difference in the waves made by a moving object by altering the speed at which it was moving.

We have a test on thursday which is when 5 of the 7 sections of our reading guide wil be due. We will have a presentation of our roller coasters on friday so bring a model or a drawing and prepare a approximately 2 minute presentation describing your coaster and giving specifics like maximum speed and its starting heights.