Week 12 Homework Assignment

 

  1. (P.435 Prob.6) Find the speed of sound in mercury, which has a bulk modulus of 2.8 x 1010Pa and a density of 1.36 x 104kg/m3.
  2. (P.435 Prob.12) (a) What is the pressure amplitude of a sound wave with an intensity level of 120.0dB in air? (b) What force does this exert on an eardrum of area 0.550 x 10-4m2?
  3. (P.4335 Prob.22) How long a pipe is needed to make a tuba whose lowest note is low C (frequency 130.8Hz)? Assume that tuba is a long straight pipe at both ends.
  4. (P.436 Prob.26) A cello string has a fundamental frequency of 65.40Hz. What beat frequency is heard when this cello string is bowed at the same time as a violin string with frequency of 196.0Hz? [Hint: The beats occur between the third harmonic of the cello string and the fundament of the violin.)
  5. (P.436 Prob.30) A source and an observer are each traveling at 0.50 times the speed of sound. The source emits sound wave at 1.0kHz. Find the observed frequency if (a) the source and observer are moving toward each other. (b) the source and observer are moving away from each; (c) the source and observer are moving in the same direction.
  6. (P.436 Prob.40) Doppler ultrasound is used to measure the speed of blood flow (see Problem 31) The reflected sound interferes with the emitted sound, producing beats. If the speed of red blood cells is 0.10m/s, the ultrasound frequency used is 5.0mHz, and the velocity of sound in blood is 1570m/s, what is the beat frequency?