```Liquid PressureJohnson, Leon                       D. H. Williams Elementary School                                    567-7026                           Objectives:

To understand Pascal's Law.
To understand Boyle's Law.
To show that water is a virtually incompressible liquid.
To understand Archimedes' Principle.

Apparatus Needed:

Rectangular bottle, 1 cork stopper, 2 rubber stoppers with opening in
the middle, open ended glass tube, Listerine bottle, gallon jug,
hammer, clear plastic dishwashing liquid bottles (Ajax or Palmolive)
with tops, medicine droppers, water, food coloring, hot water bottle, 4
meters of plastic tubing, C-clamps, metal extension rods, meter stick,
rope, 30 cm. square board, swing structure approximately 2 meters tall
made of 2"x4" wood with 60 cm. square 3/4" plywood board at top with
holes for rope drilled at corners, 4 weights (14.3 lb. exercise weights
were used in this mini-teach), 20 cm.x50 cm. plywood board.

Recommended Strategy:        Put glass tube through stopper.  Fill rectangular bottle with water.  Place a few drops of food coloring in water.  Put stopper in top of bottle.  Pass bottle around class.  Have students note what happens when the sides are squeezed.  Repeat this procedure with the Listerine bottle.  Have the class note the results of squeezing this bottle.  Ask questions as to why this happened.      Fill gallon jug with water.  Put cork stopper in top of the jug.  Compress the water by pounding stopper into the jug with a hammer.  The increased water pressure should cause the jug to break.  Explain that this illustrates Pascal's Law.      Show the class a Cartesian Diver model made from plastic soap bottle and medicine dropper.  Explain how to make one by filling the bottle with water and medicine dropper with just enough water so that head of dropper floats.  Dropper should dive when bottle is squeezed.  It should return to the top when pressure on bottle is released.  Let each class member make a Cartesian Diver.  Explain that Pascal's Law, Boyle's Law and Archimedes' Principle are illustrated in the Cartesian Diver.      Fit plastic tubing through rubber stopper.  Fit funnel on other end of plastic tubing.  Fill hot water bottle with water.  Color water with food coloring.  Secure rubber stopper in opening of hot water bottle so that water does not leak and stopper does not pop out.  Place bottle on top of 60 cm. square board at top of swing structure.  Run rope through 30 cm. square board.  Place it on top of water bottle.  Run the rope through holes in corners of the 60 cm. square board.  Place 20 cm.x50 cm. board at end of ropes for the swing.  The C-clamps should be attached to the lab table with extension rods holding the funnel and plastic tubing about 3 meters above the height of the hot water bottle.  Height of water in tube with board on top of water bottle should be calibrated as point zero.  Place one weight in swing.  Measure height of liquid in tube.  Mark off point on tube.  Continue placing weights in swing.  Record weight and height of water with each addition.  Make a graph of the weight as it changes the water height.  Have a student sit in the swing.  Measure height of liquid in tubing.  Put this point on the graph.  Draw a line connecting points to see if the line is linear or curved. ```