NATS 1720 Lecture Notes - Lecture 8: Wave, Transverse Wave, Linear Density

• School: York University
• Department: Natural Science
• Course: NATS 1720
• Professor: Carl Wolfe

Document Summary

Wave energy (for a transverse wave on a string) > for one wavelength, energy is 1/2 kinetic and 1/2 potential. A = amplitude v = wave speed eg piano wire (linear mass density) m=0. 006kg/m. Suppose a travelling wave with 1mm amplitude and frequency of 270hz. = 2 2 (0. 006 kg /m) (270 hz)(0. 0001 m)2( 408m/ s) > power of travelling wave = energy per wavelength x frequency. Energy in a sound wave doesn"t decrease, rather the amplitude of the wave decreases due to the same amount of energy being spread out over a larger radius as the sound wave travels outward. Acoustic energy in air moves away from a source with a spherical wavefronts. > energy in one wavefront spreads out as radius of spherical shell increases. Intensity decreases as square of distance from source. Total power of wave / area of sphere eg r 2 r , i 1. ^^^ = threshold ^^^ pain w/m = watt per metre.