Question

10. [-/1 Points] DETAILS SERPSE10 36.2.OP.009. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER (a) A riverside warehouse has several small doors facing the river. Two of these doors are open as shown in the figure below. Closed door B Open door Open door L The walls of the warehouse are lined with sound-absorbing material. Two people stand at a distance L - 100 m from the wall with the open doors. Person A stands along a line passing through the midpoint between the open doors, and person B stands a distance y = 20 m to his side. A boat on the river sounds its horn. To person A, the sound is loud and clear. To person B, the sound is barely audible. The principal wavelength of the sound waves is 1.60 m. Assuming person B is at the position of the first minimum, determine the distance d between the doors, center to center. (Give your answer in m.) m (b) What If? What is the minimum change in the wavelength of the sound wave for which person B would also hear a maximum at their location? (Give your answer in m.) m

Answer 1

a) This is Young's double slit inte ference for sound waves. The first minima occurs at y = 2= wavelength d= distance between slits L = distance between süt and wall La 20 As given, 100 X 160 20 = 20 100 X 1.60 ² d = - 4m 40 & distance between the doors d=4m b) For the new wavelength, the person B must be at 1st maxima, in order to hear the sound. So, formula for 1st max maxima, y = 2 x 100 AL d 20 = a' 4 2074 4 =08 m 10D ... minimun change in wavelength (2-a) = 16-0'8 - 0° 8 m.