Vibrations and Harmonics

B and C Blocks began with a discussion of how the nature of the medium impacts the speed of sound, then took on representations of sound waves and the concept of the Doppler Effect. Make sure you are very clear about how density and temperature affect sound's travel through a material, what different pictures of waves show about the true nature of sound waves and what happens to sound frequency based on how the source and observer are moving. Tomorrow, we'll take a look at forced vibrations and resonance.

E Block took on forced vibrations and resonance yesterday and F Block got that bit of information added to their coffers in class today. We discussed how a vibrating object can cause vibrations in another object and, if the vibrational frequency matches a natural frequency for the second object, we can see resonance. Folks viewed some video clips detailing the effects of resonance and how it have damaging consequences that engineers have to plan for and curtail. E Block moved from this discussion to the idea of harmonics. When a sound is produced, more than one tone may be present. Integral multiples of the main sound (fundamental frequency) are called harmonics and we looked at how harmonics play out in different types of musical instruments and contribute to the idea of music. We also took time to describe the phenomenon of beats, which is another phenomenon caused by wave interference.