A mechanical high-speed bat is flying along a path perpendicular to a wall. it emits a sound with a frequency f0. the night is clear and the air is still. let the speed of sound waves in the still air be vs. the bat hears a sound wave reflected from the wall with a frequency fnew. from this information one can determine the speed vbat at which the bat is flying. install a detector at the wall. 0 bat f v what is the detected frequency? 1. f1 = vs + vbat vs f0 2. f1 = vs vs - vbat f0 3. f1 = vs vs + vbat f0 4. f1 = vs + vbat vs - vbat f0 5. f1 = 2 vs vs - vbat f0 6. f1 = vs - vbat vs f0 7. f1 = vs - vbat vs + vbat f0 8. f1 = f0 9. f1 = 2 vs vs + vbat f0

Question

Physics

Bullwinkle

8 September, 10:23

A mechanical high-speed bat is flying along a path perpendicular to a wall. it emits a sound with a frequency f0. the night is clear and the air is still. let the speed of sound waves in the still air be vs. the bat hears a sound wave reflected from the wall with a frequency fnew. from this information one can determine the speed vbat at which the bat is flying. install a detector at the wall. 0 bat f v what is the detected frequency? 1. f1 = vs + vbat vs f0 2. f1 = vs vs - vbat f0 3. f1 = vs vs + vbat f0 4. f1 = vs + vbat vs - vbat f0 5. f1 = 2 vs vs - vbat f0 6. f1 = vs - vbat vs f0 7. f1 = vs - vbat vs + vbat f0 8. f1 = f0 9. f1 = 2 vs vs + vbat f0

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Answers (1)

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Nikolas Johns · Answer 1

1. f1 = Vs + Vbat Vs fO

2. f1 = Vs Vs - Vbat fO

3. f1 = Vs Vs + Vbat fO

4. f1 = Vs + Vbat Vs - Vbat fO

5. f1 = 2Vs Vs - Vbat fO

6. f1 = Vs - Vbat Vs fO

7. f1 = Vs - Vbat Vs + Vbat fO

8. f1 = fO

9. f1 = 2Vs Vs + Vbat fO

The observed frequency is

f = (V+Vr) * fO / (V + Vs)

The speed of the sound is V = Vs

The speed of the receiver is Vr = O

The speed of the source

Vs = - Vbat where negative is the bat which is approaching the wall

Then the correct answer is

f1 = (Vs / (Vs - Vbat)) * fO.