# physics

posted by .

A train moving with a speed of 31.8 m/s sounds a 136-Hz horn. Suppose a stationary observer sounds a horn that is identical to the one on the train. What frequency is heard from this horn by a passenger in the train.

a) 9.8 Hz
b) 31.8 Hz
c) 99 Hz
d) 115 Hz
e) 149 Hz

The fundamental of a closed organ pipe is 261.6 Hz (middle C). The second harmonic of an open organ pipe has the same frequency

what are the lengths of the closed pipe?
A)1m b) .54m C).48 m d) .33m
What are the lengths of open pipe?
A)1.31m b)1m c).37m d).24m

• physics -

First question: It depends on the relative speed the passenger has...is he going away, or coming toward the sound?

On the second question, the length of the pipe if closed on one end, is lambda/4, or length= 1/4 340/261= you do it.

The second harmonic has a length lambda, so l= 340/261= you do it.

## Similar Questions

1. ### physics

I need help with this question. A commuter train blows its horn as it passes a passenger platform at a constant speed of 55.0 m/s. The train horn sounds at a frequency of 350 Hz when the train is at rest. (a) What is the frequency …
2. ### PHYSICS

A stationary horn emits a 135-Hz tone. What frequency is heard by a passenger on a train which is moving towards this horn with a speed of 31.3 m/s?
3. ### Physics

A train sounds its horn as it approaches an intersection. The horn can just be heard at a level of 42 dB by an observer 10 km away. (a) What is the average power generated by the horn?
4. ### physics

A train is moving parallel to a highway with a constant speed of 16.0 m/s. A car is traveling in the same direction as the train with a speed of 36.0 m/s. The car horn sounds at a frequency of 504 Hz, and the train whistle sounds at …
5. ### A train sounds its horn as it approaches an inters

A train sounds its horn as it approaches an intersection. The horn can just be heard at a level of 53 dB by an observer 11 km away. (a) What is the average power generated by the horn?
6. ### physics

A train sounds its horn as it approaches an intersection. The horn can just be heard at a level of 53 dB by an observer 11 km away. (a) What is the average power generated by the horn?
7. ### Physics URGENT!!!

A train sounds its horn as it approaches an intersection. The horn can just be heard at a level of 59 dB by an observer 14 km away. (a) What (b) What intensity level of the horns sound is observed by someone waiting at an intersection …
8. ### Physics URGENT!!!

A train sounds its horn as it approaches an intersection. The horn can just be heard at a level of 59 dB by an observer 14 km away. (a) What is the average power generated by the horn?
9. ### physics

A train is moving parallel and adjacent to a highway with a constant speed of 23 m/s. A car is traveling in the same direction as the train at 46 m/s. The car’s horn sounds at 550 Hz and the train’s whistle sounds at 360 Hz. When …
10. ### physics

A stationary horn emits a 151 Hz tone. What frequency is heard by a passenger on a train which is moving towards this horn with a speed of 28.7 m/s?

More Similar Questions