In: Physics
1. A submarine (sub A) travels through water at a speed of 8.00 m/s, emitting a sonar wave at a frequency of 1,400 Hz. The speed of sound in the water is 1,533 m/s. A second submarine (sub B) is locate such that both submarines are traveling directly towards each other. The second submarine is moving at 9.00 m/s a) What frequency is detected by an observer riding on sub B as the submarines approach each other?
b) The submarines barely miss each other and pass. What frequency is detected by an observer riding on Sub B as the submarines recede from each other?
c) While the submarines are approaching each other some of the sound from sub A reflects from sub B and returns to sub A. If this sound were to be detected by an observer in sub A, what is its frequency?
2. By how much does the length of Dublin’s spire increase if its temperature increases from 0 to 20C? Assume the spire is 121 m long at 0 C and is made from stainless steel (α=12x10^-6 C-1) .