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Exam III Practice Problems (liquids and pressures)

  1. Apr 20, 2006 #1
  2. jcsd
  3. Apr 20, 2006 #2

    dav2008

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    What are the forces acting on the block?

    Can you draw a free body diagram of the block?

    The Bernoulli equation is for fluid flow so I'm not sure why (or how) you would use it here.
     
  4. Apr 20, 2006 #3
    ooo well all i have been doing for the past 4 weeks is using that eqaution for HW and stuff so i thought it must be it. Anywyas, You have the Water pushing up, Wood Pushing down and String pulling down
     
  5. Apr 20, 2006 #4

    dav2008

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    Right. You have the buoyant force acting upwards, the weight of the block acting downwards and tension acting downwards.

    Can you see how to solve for tension now?
     
  6. Apr 20, 2006 #5
    Edit:Never mind
     
  7. Apr 20, 2006 #6

    dav2008

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    You are given the volume of the block and its density. Using those facts you can find its mass.

    As far as the forces, like you said earlier there are only 3 forces: Tension down, weight down, and buoyancy up.

    Recall Archimedes' principle that the buoyancy force is equal to the weight of the displaced fluid.
     
  8. Apr 20, 2006 #7
    thanks, I'll be back with more in 5 min. :)
     
  9. Apr 20, 2006 #8
    ya i got it, there are too many stuff that are same like V= Velocity but then it is Volume in that equation. Crazy
     
  10. Apr 20, 2006 #9
  11. Apr 20, 2006 #10

    dav2008

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    Well given that it's a multiple choice you can just see which one of those three equations fits your given information.

    You're given that at t=0 s v=11.1 m/s.
     
  12. Apr 20, 2006 #11
  13. Apr 20, 2006 #12

    dav2008

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    Well try it and see if you get the right answer.
     
  14. Apr 20, 2006 #13
    :( nope well i was thinking of using X(t) = A cost(omega t) but what would A be hmmmm
     
  15. Apr 20, 2006 #14
    Im stupid. I got it
     
    Last edited: Apr 20, 2006
  16. Apr 20, 2006 #15
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