What equation do I use?

  • Thread starter jjlandis
  • Start date
  • #1
12
0

Homework Statement


Earthquakes produce several types of shock waves. The most well-known are the P-waves and the S-waves. In the earth’s crust, the P-waves travel around 7.0 km/s while the S-waves move at about 3.6 km/s. The time delay between the arrival of these two waves at a seismic recording station tells geologists how far away the earthquake occurred. If the time delay is 19 s, how far away from the seismic station did the earthquake occur?
Answer in book is 140.8 m but I can't make it to that answer. Any help would be great.
Thanks.


Homework Equations






The Attempt at a Solution


Tried to find the x distance by using: X-Xo = ((Vox + Vx)*.5)*t
 

Answers and Replies

  • #2
LowlyPion
Homework Helper
3,097
5

Homework Statement


Earthquakes produce several types of shock waves. The most well-known are the P-waves and the S-waves. In the earth’s crust, the P-waves travel around 7.0 km/s while the S-waves move at about 3.6 km/s. The time delay between the arrival of these two waves at a seismic recording station tells geologists how far away the earthquake occurred. If the time delay is 19 s, how far away from the seismic station did the earthquake occur?
Answer in book is 140.8 m but I can't make it to that answer. Any help would be great.
Thanks.

Homework Equations



The Attempt at a Solution


Tried to find the x distance by using: X-Xo = ((Vox + Vx)*.5)*t

The average velocity isn't going to identify the distance now is it since you don't know the actual time really. They arrive at different times.

But they do arrive from the same distance X.

Vs*ts = xs

Vp*tp = xp

where xs = xp = X

Consider then Δt between the slow one and the fast one. That gives you distance then doesn't it? And they do give you conveniently Δt.
 

Related Threads on What equation do I use?

  • Last Post
Replies
6
Views
2K
Replies
3
Views
2K
Replies
1
Views
2K
  • Last Post
Replies
3
Views
1K
  • Last Post
Replies
10
Views
1K
  • Last Post
Replies
1
Views
1K
  • Last Post
Replies
7
Views
2K
  • Last Post
Replies
1
Views
1K
  • Last Post
Replies
1
Views
1K
  • Last Post
Replies
3
Views
1K
Top