1. Sound waves are produced by a point source. Smart students from BMCC decide to measure the intensity of the sound waves at a distance 200 m from the sound source. They measure that the intensity is 100 dB. Now they want to find a location where a person can tolerate the sound intensity of 80 dB. Find the distance to that point from the sound source in m.
2. While standing at a point on the roadside shoulder, a police car chasing a speeder was approaching you. At that moment you hear the siren of the police car at a frequency of 560 Hz. When the police car passes, the frequency of the siren changes to 480 Hz. What was the speed of the police car in m/s if you assume that the speed of sound is 360 m/s?
3. You approach with a vibrating tuning fork above a resonating tube (one end closed) that is filled with water at a certain level. The tuning fork resonates when a height of air column is 0.150 m and again 0.450 m. What is the frequency in Hz of the fork when the speed of sound is taken to be 340 m/s?
4. You are performing an experiment on waves on a copper wire that is taut with fixed ends under appropriate tension of 1,260 N. If the diameter of the wire is 1.50 mm and its density is 8.93 g/cm3, what is the speed of the waves traveling on the wire in m/s?
5. A string of length L = 2.0 m is held with both ends fixed. Now it is vibrating with a frequency 120 Hz by an external source, and the vibration creates a standing wave with three nodes including the both ends. What is the natural fundamental frequency of the string in Hz?