The Tired Swimmer: A Case Study

Can somebody explain to me how newton's 3rd law relates to momentum? ~ap physics 1

Two loudspeakers, 5.5 m apart and facing each other, play identical sounds of the same frequency. you stand halfway between them, where there is a maximum of sound intensity. moving from this point toward one of the speakers, you encounter a minimum of sound intensity when you have moved 0.33 m . assume the speed of sound is 340 m/s. part a) what is the frequency of the sound? part b) if the frequency is then increased while you remain 0.21 m from the center, what is the first frequency for which that location will be a maximum of sound intensity? express your answer to two significant figures and include the appropriate units.

A90db sound wave strikes an eardrum whose area is 5.0×10^-5m^2. how much energy is absorbed by the eardrum per second