Swamped with Sound

Physics D and Honors Physics discussed the concepts of timbre and beats today in class. We used our work with harmonics to discuss the musical quality of sound and why different instruments, playing the same note, sound quite differently due to the numbers and intensities of harmonics each instrument produces. We then turned attention to beats, which is an interference phenomenon where two waves of similar frequencies produce a resultant wave with alternating soft (destructive) and loud (constructive) regions. The numbers of beats/second, or beat frequency equals the frequency difference between the incident waves. Tomorrow we review and Thursday is our exam, so come to class tomorrow with questions.

Physics D conducted two lab investigations, one that centered on sound production and beats and the other on standing waves. Students compared properties of waves produced by two different tuning forks struck separately and when they were struck simultaneously. The interference of the waves produced beats with, when the frequency was calculated, was equal to the frequency difference between the two tuning forks. Folks then generated standing waves on a string and measured properties such as wavelength, frequency and wave speed. As wavelength decreased, frequency increased so that the speed of the wave in the rope remained constant. We'll discuss this lab tomorrow, along with the idea of timbre and beats before reviewing for Thursday's exam.

Intro Physics discussed the relationship between work and heat. We looked at how doing work on a system can raise its internal energy and temperature and how a system doing work can experience a decrease in internal energy and temperature. We touched on the concept of thermodynamics and discussed how heat, work and internal energy are related in both heat engines and refrigeration systems. Tomorrow, we begin on phases of matter and phase chnge.