Problems Ch 12 P: 9, 10, 11, and 12 were presented today. We will finish with our presentations of our solutions to 16 and 18 tomorrow.
Sound levels in decibels provide a good scale for our perception of loudness. And that's what we dealt with today. Every interval of 10 dB in sound level is due to a 10-fold increase in intensity and energy flow in a sound wave. Every 10 dB increase in sound level is a result of an increase of ten times the intensity. Therefore, a 20 dB increase in sound level is the result of 10 dB + 10 dB, which is two increases of ten times in the intensity of the sound input. That's an increase in intensity of 100-fold.
We also saw that doubling the intensity results in a 3 dB increase in sound level. Increasing the intensity of a sound 4 times results in a 3dB + 3dB increase in sound level, or 6dB. Assignment:
We presented our solutions to Ch 12 P: 4, 5, 7 today. Problem 5 requires some clear thinking about what we know and the simple relationships among these known quantities...and the quadratic equation, too.
You should know the frequency range of human hearing, too, from our 'hearing test' today. Assignment:
We considered natural phenomena like the time between a lightning stroke and the thunder clap. The speed of sound can help us figure out the distance to the lightning. Then we had some time to work on our assignments for tomorrow.
Assignment:
Now that we have our data we discussed how to analyze our data and to write a lab report. The grading scheme for our lab reports is here.
Assignment:
Sound is the phenomenon of choice for Chapter 12. It's a longitudinal wave, and our first goal is to find out how fast sound travels in air. So today we learned how to hook up our microphones to your computers in order to collect data. And some of us figured out exactly what data we are looking for. We will continue this tomorrow.
Assignment:
Today was the test for Chapter 11.
Assignment:
We reviewed wave intensity problems 46 and 47 mostly today in preparation for tomorrow's Ch 11 test.
For our Celebration on Tuesday you should be able to identify from diagrams and to describe in words the reflection, the refraction, the diffraction, and the interference of waves.
You also should be able to sketch standing wave diagrams for the fundamental and the 2nd, 3rd, 4th, etc. harmonics for a vibrating string like the one we saw in class. Assignment:
And prepare for Tuesday's Ch 11 Waves exam. |
Physics II
Mr. Swackhamer Scottsdale Preparatory Academy Archives
March 2020
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