Turn on thread page Beta
    • Thread Starter
    Offline

    14
    ReputationRep:
    Link to paper: http://www.ocr.org.uk/Images/61757-q...nian-world.pdf

    I'm doing question 4 on the 2011 January past paper, I did all the first parts of the questions completly fine until I got to the last part, part (iii) where you have to give and expression for the depth of the water.

    I got d = 2.5cos(1.39x^10-4 x t)

    but in the mark scheme the answer is what I have but plus 15.5:

    d = 15.5 + 2.5cos(1.39x10^-4 x t)

    My question is why is it plus 15.5. Is it the Amplitude minus the max water level, but I don't understand why that needs to be added. Please let me know why the 15.5 is there. Thanks


    Link to paper: http://www.ocr.org.uk/Images/61757-q...nian-world.pdf
    Offline

    17
    ReputationRep:
    (Original post by Reda2)
    Link to paper: http://www.ocr.org.uk/Images/61757-q...nian-world.pdf

    I'm doing question 4 on the 2011 January past paper, I did all the first parts of the questions completly fine until I got to the last part, part (iii) where you have to give and expression for the depth of the water.

    I got d = 2.5cos(1.39x^10-4 x t)

    but in the mark scheme the answer is what I have but plus 15.5:

    d = 15.5 + 2.5cos(1.39x10^-4 x t)

    My question is why is it plus 15.5. Is it the Amplitude minus the max water level, but I don't understand why that needs to be added. Please let me know why the 15.5 is there. Thanks


    Link to paper: http://www.ocr.org.uk/Images/61757-q...nian-world.pdf
    The depth of the water at time t would be the 'resting' water level plus the displacement due to the tide. The resting level would be the midpoint of 13 and 18, so 15.5. I can't think of a better way to describe resting level but if you just imagine there is no tide and the water isn't undergoing simple harmonic motion, or the water level when the displacement is 0.

    Does that make sense?
    • Thread Starter
    Offline

    14
    ReputationRep:
    (Original post by Alex621)
    The depth of the water at time t would be the 'resting' water level plus the displacement due to the tide. The resting level would be the midpoint of 13 and 18, so 15.5. I can't think of a better way to describe resting level but if you just imagine there is no tide and the water isn't undergoing simple harmonic motion, or the water level when the displacement is 0.

    Does that make sense?
    Yes it does, thank you very much! I understand it now.
 
 
 
Reply
Submit reply
Turn on thread page Beta
Updated: March 15, 2016

University open days

  • University of Bradford
    All faculties Undergraduate
    Wed, 21 Nov '18
  • Buckinghamshire New University
    All Faculties Postgraduate
    Wed, 21 Nov '18
  • Heriot-Watt University
    All Schools Postgraduate
    Wed, 21 Nov '18
Poll
Black Friday: Yay or Nay?

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.