Turn on thread page Beta

Can anyone help with this seismic reflection problem? watch

    • Thread Starter
    Offline

    0
    ReputationRep:
    I know that a reflection from a horizontal reflector arrives at a coincident source and reciever at a two-way time of 0.133 seconds. At a reciever 200m away from the source the same reflection has a two-way time of 0.149 seconds.

    I have to work out the velocity to the reflector.

    So far I've drawn a diagram that looks like the image attached.

    Everything I try and work out I end up not having all the information to do it. If anyone could explain how to do it I would be very grateful.
    Attached Files
  1. File Type: docx Seismic reflection.docx (27.4 KB, 71 views)
    Offline

    10
    You have a large right angled triangle in the diagram and can apply Pythagoras' Theorem for the length of the 3 sides.
    Top side is 200m
    Hypotenuse (red) is 0.149 x speed of wave
    Other side (green) is 0.133 x speed of wave.
    • Thread Starter
    Offline

    0
    ReputationRep:
    (Original post by Stonebridge)
    You have a large right angled triangle in the diagram and can apply Pythagoras' Theorem for the length of the 3 sides.
    Top side is 200m
    Hypotenuse (red) is 0.149 x speed of wave
    Other side (green) is 0.133 x speed of wave.
    So:

    (0.149xV)2 = 2002 + (0.133xV)2

    and I have to use that to work out what V is?

    Thank you for trying to help. Sorry, I'm really not good at maths and physics and haven't done any of either for nearly 4 years so I may sound really stupid.
    Offline

    10
    That's correct.
    Multiply out the terms (you'll get v squared) and collect the v squareds on one side of the equation.
    (0.149 x 0.149) x V^2 = 200^2 + (0.133 x 0.133) x V^2 to start you off.
    Then
    (0.0222)V^2 + (0.17689)V^2 = 200^2
    then
    ( )V^2=200^2
    Then
    V^2 =
 
 
 
Reply
Submit reply
Turn on thread page Beta
Updated: February 11, 2010
The home of Results and Clearing

1,096

people online now

1,567,000

students helped last year

University open days

  1. University of Buckingham
    Postgraduate Open Evening Postgraduate
    Thu, 23 Aug '18
  2. University of Glasgow
    All Subjects Undergraduate
    Tue, 28 Aug '18
  3. University of Aberdeen
    Undergraduate Open Day Undergraduate
    Tue, 28 Aug '18
Poll
How are you feeling about GCSE results day?

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Write a reply...
Reply
Hide
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.