BUOYANCY PARADOX - BALL IN TWO LIQUIDS

[Fu-Kwun Hwang]

This is a question from The Physics Question of the Week at Univ. of Mrayland.

A ball floats on water, as seen in the photograph below, but will sink when put into mineral spirits. The water is dyed green with food coloring to distinguish it from the clear mineral spirits. Note how far the floating ball sinks into the water.

When the mineral spirits is poured slowly onto the top of the water, it will remain on top because the two fluids are immiscible.

If the mineral spirits is poured slowly on top of the water while the ball is floating on the water, what will happen to the level at which the ball floats?

   * (a) The ball will float lower into the water.
   * (b) The ball will float higher out of the water.
   * (c) The ball will float at the same level with respect to the surface of the water after the mineral spirits are poured on top of the water.

The following simulation will let you play with the above experiment with java applet.
An object with density d2 is floating on a liquid with density d1. (d1>d2)
You can drag h3 to add another liquid with density d3 to find out what will happened to the object d2.
You can change density for d1,d2,d3 and height for those two liquid.
Click showp to find out how the pressure changed.
I hope you can enjoy playing with this applet and learn more about buoyancy force (liquid pressure as well)

Embed a running copy of this simulation
<applet code='users.ntnu.fkh.buoyancy2level_pkg.buoyancy2levelApplet.class' archive='http://www.phy.ntnu.edu.tw/ntnujava/ejsuser/2/ejs_buoyancy2level.jar' name='buoyancy2level1292' id='buoyancy2level1292' width='562' height='422' mayscript=true><param name='draggable' value='true'></applet>
Embed a running copy link(show simulation in a popuped window)
<a href='http://www.phy.ntnu.edu.tw/ntnujava/msg.php?smfejs=1292' target='smfejs'>Run simulation</a>

Full screen applet or Problem viewing java?Add http://www.phy.ntnu.edu.tw/ to exception site list
Press the Alt key and the left mouse button to drag the applet off the browser and onto the desktop. This work is licensed under a Creative Commons Attribution 2.5 Taiwan License

• Please feel free to post your ideas about how to use the simulation for better teaching and learning.
• Post questions to be asked to help students to think, to explore.
• Upload worksheets as attached files to share with more users.

Let's work together. We can help more users understand physics conceptually and enjoy the fun of learning physics!

[carlprince2009]

  The food coloring gives a volume in addition of the water in because of that.

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