Amoving sound source a has a velocity (85 km/hr) \widehat{i\ } and a moving reflecting surface b has a velocity (75 km/hr) (-\ \widehat{i\ }). the source a emits a sound with a frequency of 39 khz. a) assuming b is approaching a find the frequency as heard by b b) assuming b is moving away from a, find the frequency as heard by b c) what is the frequency of the reflected beam to the source (pick (b) as the set-up to answer this question). speed of sound in air 340 m/s

see earlier

speed of light in vacuum is 300,000 km/s

speed of light in other mediums is given by the expression v = c/n, where c is the speed of light in vacuum and n is the refractive index of medium.

for the first medium v = 200,000 km/s

  so, refractive index of medium = 300000/200000 = 1.5

    1.5 refractive index is usually for glass. so first medium is glass.

for the second medium v = 250,00 km/s

so, refractive index of medium = 300000/250000 = 1.2

    1.2 refractive index is usually for water. so second medium is water.

for the third medium v = 0 km/s

so, refractive index of medium = 300000/0 = ∞

    ∞ refractive index is usually for opaque mediums. so third medium is opaque medium.