CT17-1A listener measures the sound intensity from a loud source of sound and finds that the intensity is 90dB. He moves 10 times further from the source of the sound. The sound intensity measured by the listener is now most nearly:A: 80dB B: 70dB C: 60dB D: 50Db E: 40dBCh17-2.A string is clamped at both ends and then plucked so that it vibrates in a standing mode between two extreme positions a and c.Let upward motion correspond to positive velocities. When the string is in position b, the instantaneous velocity of points along the string is...A: zero everywhere. B: positive everywhere.C: negative everywhere. D: depends on the position.Answer: depends on position.a b c node: never moves.Ch17-3.A string is clamped at both ends and then plucked so that it vibrates in a standing mode between two extreme positions a and c.Let upward motion correspond to positive velocities. When the string is in position c, the instantaneous velocity of points along thestring is...A: zero everywhere. B: positive everywhere.C: negative everywhere. D: depends on the position.abcCh17-4.A trombone is played in a room where the air has been replaced with helium. In helium, the speed of sound is about 2X the speed of sound in air. The frequency of the trombone notes are found to be ..A) The same.B) Too high by a factor of 2C) Too low by a factor 2D) Too high by a factor of 4E) Too low by a factor of 4CT17-5A musician playing a perfect "concert A" tone (f = 440Hz) on his horn is standing on the back of a fast-moving pickup truck which drives by a listener standing on the sidewalk. The truck has constant velocity.Which graph below most accurately shows the frequency heard by the listener vs. time?listenertruck-ridin'
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