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Pressure & Buoyant Force
BlackBoard Notes

======================= Photo - Click for a Larger Version =============================

blackboard image

RATS! I made a typo on the board notes. The yellow vector in the third section
equation is Twater, not Tair! Need new photo Fall 2026!

======================= First Board Section =============================

Part I: Pressure – Depth Relation:

Can
Force Diagram: forces when floating:
Fb – Fg = 0

Keep the Sand Dry!

  • Pressure on bottom of jar:

    Pressure

    .

  • Pressure at depth h below water surface:

    P = ρwgh

    (draw arrow and write:) "rho" - density of water

  • Keep the sand dry!

    ======================= Second Board Section =============================

    Part II: Archimedes' Principle: "The buoyant force equals the weight of the volume of the displaced fluid"

    .

  • Block

     
     

    In Air!
    Tair – Fg = 0

    Forces

    In Water!
     

     

    ======================= Third Board Section =============================

     

  • When the block is suspended in water:

     

  • Return to Setup

    © St. Lawrence University Department of Physics
    Revised: 14 Jul 26 Canton, NY 13617