Welcome to ScubaBoard, an online scuba diving forum community where you can join over 205,000 divers diving from around the world. If the topic is related to scuba diving, this is the place to find divers talking about it. To gain full access to ScubaBoard (and make this large box go away) you must register for a free account. As a registered member you will be able to:

  • Participate in over 500 dive topic forums and browse from over 5,500,000 posts.
  • Communicate privately with other divers from around the world.
  • Post your own photos or view from well over 100,000 user submitted images.
  • Gain access to our free classifieds marketplace to buy, sell and trade gear, travel and services.
  • Use the calendar to organize your events and enroll in other members' events.
  • Find a dive buddy or communicate directly with scuba equipment manufacturers.
All this and much more is available to you absolutely free when you register for an account, so sign up today!

If you have any problems with the registration process or your account login, please contact the ScubaBoard Support Team.
Page 1 of 8 123456 ... LastLast
Results 1 to 10 of 78
Like Tree34Likes

Thread: Test your buoyancy understanding!

 


  1. #1
    Registered


    Has not set a "status"
     

    Join Date
    May 2012
    Location
    Ploiesti, Romania
    Posts
    14
    Dives
    0 - 24

    Test your buoyancy understanding!

    Hey, just a bit of fun, test your understanding of buoyancy / diving related physics.

    2 (easyish) questions for now...

    - You have a canoe in a swimming pool with a rock inside the canoe. You throw the rock out of the canoe into the water. What happens to the level of the swimming pool?

    - You have a canoe with a rock hanging off the front on a rope, completely submerged with water. If you cut the rope what happens to the level of the swimming pool?

    Also explain your answer!

  2. #2
    Registered


    I wanna dive...
     

    Join Date
    Mar 2011
    Location
    The Water
    Posts
    406
    Dives
    200 - 499
    1. The level stays the same. Even if the rock was in or out of the canoe it doesn't change the fact that there's a rock and a canoe in the pool. Therefore the level will stay the same

    2. Stays the same. Same reason as the first question
    Mark Derail likes this.
    It's dive o'clock somewhere...
    Friends don't let friends deal with AquaLung customer support.

  3. #3
    Defender!


    Soon, very soon...
     

    Tigerman's Avatar
    Join Date
    Nov 2006
    Location
    Norway
    Posts
    5,577
    Dives
    I just don't log dives
    Photos
    100
    What happens is that you break the tiles on the bottomn of the pool, which makes the maintenance people VERY pissed off..
    If your face aint numb.. It aint a cold water dive!
    I wonder if periodic short term exposure to risk can decrease your longterm risk of accidents. I hope it does..

    The best video ever for a diver to watch - The divers ear http://faculty.washington.edu/ekay/
    a lesson learned - Blown o-ring AT DEPTH!: http://www.scubaboard.com/forums/nea...g-depth-o.html

  4. #4
    Registered


    Has not set a "status"
     

    Join Date
    May 2012
    Location
    Ploiesti, Romania
    Posts
    14
    Dives
    0 - 24
    Quote Originally Posted by SnorkelLA View Post
    1. The level stays the same. Even if the rock was in or out of the canoe it doesn't change the fact that there's a rock and a canoe in the pool. Therefore the level will stay the same

    2. Stays the same. Same reason as the first question
    Nope! Tho that is what most people would answer.
    eelnoraa likes this.

  5. #5
    Chairman of the Board


    is dreamin about diving.
     

    NetDoc's Avatar
    Join Date
    Jan 2001
    Location
    Key Largo, Florida, United States
    Photos
    1511
    English or African rock?
    Solo otro día en el paraíso!

    How you train makes a difference!
    Learn Scuba without kneeling: NetDocScuba.com

    Pete "NetDoc " Murray

  6. #6
    Divemaster
    Badge


    Nova Scotia Divemaster
     

    TMHeimer's Avatar
    Join Date
    Dec 2007
    Location
    Murphy Cove, Nova Scotia (Eastern Shore), Canada
    Posts
    3,873
    Dives
    200 - 499
    Quote Originally Posted by xozzx View Post
    Nope! Tho that is what most people would answer.
    That would've been my first guess. Does it have to do with the rock at first either being out of the water (in the canoe) or tied to the canoe which is not completely submerged--thus the end result being the water level rising? Displacement obviously has something to do with it, no? NO-- wait wait... When the rock is in or attached to the canoe the canoe plus rock is considerably heavier and thus displaces more water over a wide area than when the rock is on the bottom, so the water level goes down. The rock's water displacement is very small compared to the conoe's. How's that?
    "If we lived here we'd be home".--Bob Miller
    To be is to do--Socrates.To do is to be--Plato.Do be do be do--Sinatra.

  7. #7
    New User


    Has not set a "status"
     

    Join Date
    Aug 2011
    Location
    Maryland
    Posts
    2
    Dives
    0 - 24
    Thank you, LOL!!!

  8. #8
    Senior Moderator


    all things in moderation...
     

    diversteve's Avatar
    Join Date
    Apr 2004
    Posts
    13,518
    Dives
    I'm a Fish!
    Photos
    3
    In both instances the water level decreases slightly. The first because you're reducing the displacement of the canoe hull when you throw the rock overboard.

    The 2nd is similar but the water level should decrease less because the weight of the rock in water will be slightly less as it's more buoyant (yes rocks are buoyant - just not very) so it is pulling the canoe hull down slightly less. It's less of a net change because the rock is already displacing it's volume in the water.

    You have a canoe with a rock hanging off the front on a rope, completely submerged with water.
    However, the way you wrote this - if the canoe itself is completely submerged in the water - the net change is zero...lol
    KWS likes this.

  9. #9
    is blessed by God


    Who is John Galt?
     

    Insta-Gator's Avatar
    Join Date
    Jul 2008
    Location
    Georgia 50 weeks, Bonaire 1 week, Grand Cayman 1 week
    Dives
    100 - 199
    Photos
    68
    What type of rock and it's related specific gravity?
    Insta-Gator
    aka Gary

    In support of my son and the brave men and women of the 3-17 Cavalry as they serve far from home. God bless and keep you.

    Question of the day: Does God love me for some unexplained reason and blessed me with a wonderful wife - OR - Did God bless me with a wonderful wife and, therefore, has learned to love me for her sake?

  10. #10
    Divemaster
    Badge


    Nova Scotia Divemaster
     

    TMHeimer's Avatar
    Join Date
    Dec 2007
    Location
    Murphy Cove, Nova Scotia (Eastern Shore), Canada
    Posts
    3,873
    Dives
    200 - 499
    The rock's water displacement is accounted for no matter where is is, but the canoe's displacement decreases with no rock in it or attatched to it. So the water level decreases.
    KWS likes this.
    "If we lived here we'd be home".--Bob Miller
    To be is to do--Socrates.To do is to be--Plato.Do be do be do--Sinatra.

Page 1 of 8 123456 ... LastLast

Similar Threads

  1. Test Your Reflexes
    By The Anchor in forum Humor, Games, Clips, Yarns and Tales
    Replies: 8
    Last Post: June 19th, 2008, 01:48 PM
  2. Do you test your nitrox?
    By fisherdvm in forum Basic Scuba Discussions
    Replies: 78
    Last Post: May 28th, 2007, 08:38 PM
  3. Photographers please work on your buoyancy
    By mjh in forum Underwater Photography
    Replies: 32
    Last Post: January 18th, 2006, 08:16 PM
  4. DIVE PROBLEM... test your physics!
    By KangarooSeatbelt in forum Marine Science and Physiology
    Replies: 11
    Last Post: December 12th, 2004, 07:49 AM
  5. Do You Test Your Regs? Both? Every Dive?
    By DandyDon in forum Basic Scuba Discussions
    Replies: 20
    Last Post: June 28th, 2004, 10:49 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •