Calculating Maximum Oscillation: Point Sources and Out of Phase Waves

[LandOfStandar]

[SOLVED] Out of Phase waves

Homework Statement

Straight line AB connects two point sources that are 5.00m apart, emit 300Hz sound waves of the same amplitude, and emit exactly out of phase. (a) What is the shortest distance between the midpoint of AB and a point on AB where the interfering waves cause maximum oscillation of the air molecules? What are the (b) second and (c) third shortest distance?

Homework Equations

and

The Attempt at a Solution

(delta L)/(wavelength) = .5, 1.5, 2.5 ...
(wavelength) = v/f = (velocity of molecules in the air)/f = 330/300 = 1.1m <- I don't think . that is right
(delta L) = (2.5 + x) - (2.5 - x) = 2.5 + x - 2.5 + x = 2x

I am I approaching this right, if not do you have any suggestions to sat me straight.

 

[LandOfStandar]

Can anyone please help me? I have spent hours on this and just need to know if anyone has suggestion on the approach to get me started.

 

[LandOfStandar]

why is no one helping, I don't know what to do?

 

[Doc Al]

(delta L)/(wavelength) = .5, 1.5, 2.5 ...

Good.

(wavelength) = v/f = (velocity of molecules in the air)/f = 330/300 = 1.1m <- I don't think . that is right

Also good, if you take the speed of sound in air (which is not the velocity of the molecules) to be 330 m/s. (Sound speed depends on temperature, but close enough.)

(delta L) = (2.5 + x) - (2.5 - x) = 2.5 + x - 2.5 + x = 2x

Good. You are on the right track. Don't stop now.

 

[LandOfStandar]

the answer in the book don't match mine

 

[LandOfStandar]

If I continue
I get ...
(2x)/(1.1) = .5, 1.5, 2.5 ...
x= (.5, 1.5, 2.5 ...)(1.1)/(2) = 0.275, 0.825, 1.1375
answers 0, 0.572, 1.14

 

[Doc Al]

I agree with your answers, not the book's. What book are you using?

 

[LandOfStandar]

Fundamentals of Physic, by Halliday Resnick

Ok, if that looks right I will send it in that way thanks!

https://www.physicsforums.com/showthread.php?t=216294"
This is the other frequency question that I don't know how to approach.
Thanks for the help!