Apopular car stereo has four speakers, each rated at 60 w. in answering the following questions, assume that the speakers produce sound at their maximum power.

a) find the intensity i of the sound waves produced by one 60-wspeaker at a distance of 1.0 m.

4.8 w/m^2

b) find the intensity i of the sound waves produced by one 60-wspeaker at a distance of 1.5 m.

2.1 w/m^2

c) find the intensity i of the sound waves produced by four 60-wspeakers as heard by the driver. assume that the driver is located 1.0 m from each of the two front speakers and 1.5 m from each of the two rear speakers.

13.8 w/m^2

d)the threshold of hearing is defined as the minimum discernible intensity of the sound. it is approximately 10^(-12) w/m2. find the distance dfrom the car at which the sound from the stereo can still be discerned. assume that the windows are rolled down and that each speaker actually produces 0.06 w of sound, as suggested in the last follow-up comment.

d=

The particle in a two-dimensional well is a useful model for the motion of electrons around the indole ring (3), the conjugated cycle found in the side chain of tryptophan. we may regard indole as a rectangle with sides of length 280 pm and 450 pm, with 10 electrons in the conjugated p system. as in case study 9.1, we assume that in the ground state of the molecule each quantized level is occupied by two electrons. (a) calculate the energy of an electron in the highest occupied level. (b) calculate the frequency of radiation that can induce a transition between the highest occupied and lowest unoccupied levels. 9.27 electrons around the porphine ring (4), the conjugated macrocycle that forms the structural basis of the heme group and the chlorophylls. we may treat the group as a circular ring of radius 440 pm, with 20 electrons in the conjugated system moving along the perimeter of the ring. as in exercise 9.26, assume that in the ground state of the molecule quantized each level is occupied by two electrons. (a) calculate the energy and angular momentum of an electron in the highest occupied level. (b) calculate the frequency of radiation that can induce a transition between the highest occupied and lowest unoccupied levels.