Acoustics and Sound Waves: Principles, Calculations, and Applications1. Standing waves have regions of minimum amplitude callednodesand regions ofmaximum amplitudecalledantinodes.-----------------------------------------------------------------------------------------------------------------------------2. Thedecibelscale is a logarithmic scale used for comparing sound levels.-----------------------------------------------------------------------------------------------------------------------------3. An open organ pipe (both ends open), 16 feet long, is operating in air at 20°C. Thefundamentalfrequency f1 = __________ Hz and the second harmonic frequencyf2 = __________ Hz (1 ft = 0.3048m).in a pipe open at both ends, the natural frequencies of oscillation form a harmonicseries that includesall integral multiples of the fundamental frequency:𝑓𝑛=𝑛𝑣𝐿𝑛=1,2,3,…Therefore:𝑓1=𝑣𝐿=343(16∗0.3948)=𝟓𝟒.𝟑𝑯𝒛𝑓2=2×𝑣𝐿=2×343(16∗0.3948)=𝟏𝟎𝟗𝑯𝒛-----------------------------------------------------------------------------------------------------------------------------4. Suppose the air is replaced by helium at 20°C (v= 1005 m/s). For an open pipe (both endsopen), 16-ftin length, the new fundamental frequencyf1 = __________ Hz.𝑓1=𝑣𝐿=1005(16∗0.3948)=𝟏𝟓𝟗𝑯𝒛-----------------------------------------------------------------------------------------------------------------------------5. In order to produce a fundamental frequency of 10 Hz in a stopped organ pipe (one end closed),therequired lengthL= __________ m.𝑓1=𝑣𝐿==>𝐿=𝑣𝑓1=34310=𝟑𝟒.𝟑𝒎Preview Mode
This document has 5 pages. Sign in to access the full document!