• Support PF! Buy your school textbooks, materials and every day products Here!

Sound Waves of explosion

  • Thread starter candyq27
  • Start date
  • #1
71
0

Homework Statement


An explosion occurs at the end of a pier. The sound reaches the other end of the pier by traveling through three media: air, fresh water, and a slender metal handrail. The speeds of sound in air, water, and the handrail are 343, 1482, and 5040 m/s, respectively. The sound travels a distance of 150 m in each medium.
(a) Through which medium does the sound arrive first, second, and third?

(b) After the first sound arrives, how much later do the second and third sounds arrive?

Homework Equations


v=sqrt(B/density)



The Attempt at a Solution



We just started going over waves and sound so I'm not sure how to figure out this problem.
For part (a) I figured out that the sounds arrives first at the steel handrail, then freshwater then air.
For part (b) I don't know how to figure that out. I tried just doing how many seconds it would take to travel 150m for each substance, but I don't think that's right.
 

Answers and Replies

  • #2
5,428
291
Well, the problem states the speed of sound in each medium, so you can get how long it takes in each medium using,

time = distance/velocity
 
  • #3
71
0
So first it went through the steel handrail so that is 150/5040= 0.02976s, then through the water so 150/1432= 0.1047s, then the air so 150/343=0.4373s.
So the first sound happens after 0.03s, then the second sound comes after 0.1047s, then the third sound comes after 0.4373s. Right?
 
  • #4
71
0
I get that the third sound comes 0.41s because you have to do 0.437-0.03, but I can't figure out how to get the second sound...?
 
  • #5
340
0
The question asks how much later do the second and third arrive as compared to the first. You have done most of the work.
 
  • #6
71
0
Well for the second I did 0.105-0.03 and it's incorrect...?
 
  • #7
5,428
291
(a) Through which medium does the sound arrive first, second, and third?
This implies that the sound travels in parallel throught the media, not through each in turn.
Otherwise it would always arrive in the last medium in the chain making the question meaningless.
 

Related Threads on Sound Waves of explosion

  • Last Post
Replies
8
Views
3K
  • Last Post
Replies
1
Views
2K
  • Last Post
Replies
6
Views
7K
  • Last Post
Replies
1
Views
810
Replies
1
Views
7K
  • Last Post
Replies
1
Views
399
  • Last Post
Replies
3
Views
1K
  • Last Post
Replies
2
Views
4K
  • Last Post
Replies
1
Views
5K
  • Last Post
Replies
3
Views
452
Top