Category Archives: Fluid Mechanics

Constant Velocity Tubes

Demo: FM-C-VT
Pira Index: 2C 30.25

Lab Equipment  Directions
  1. Mounted velocity tubes
Note: The red, orange, and yellow tubes contain CHEVRON Hydraulic oil AW ISO 22. The green, blue, and violet tubes contain CITGO A/W Hydraulic Oil 46.
If tubes break – thoroughly wash and rinse any body part that may have touched the substance.
  1. Invert the tubes and watch the bubble rise at different times.
  2. Have students time the bubbles and plot graphs of position versus time.

Buoyancy Film Canister

Demo: FM-B-BC
Pira Index: 2B 40.00

Lab Equipment  Directions
  1. film canister set with 9 large shots and 1 small shot
  2. large clear tank filled 3/4 with water
Note: Please make sure shots are dry before putting them away to pre
  1. Place 8 shots in canister and release in water about midway down. Canister should float above water level.
  2. Place 9 shots in canister and release in water about midway down in water. Canister should rise to water level and stay.
  3. Place small shot with 9 large shots in canister. Before placing in water ask students to predict what will happen? Continue to flot? Hover in the middle? Sink to the bottom?
  4. Place canister in water and release midway. Canister should slowly sink to the bottom.

Two – Liter Smoke Rings

Demo: FM-C-TL
Pira Index: 2C 50.15

Lab Equipment  Directions
  1. plastic drinking bottle
  2. incense stick and matches
  3. propane torch
  4. 35mm projector (or OHP)
(can also use large drinking cup with circular hole cut in bottom and balloon rubber stretched over the open end)
  1.  Light two inches of the incense stick with the torch.
  2. Place burning stick into bottle held upside down.
  3. Fill the bottle with smoke.
  4. Turn off room lights and use 35mm or OHP to make the smoke more visible.
  5. Remove stick and hold the bottle upright and squeeze.

Note: small easy squeezes work best.

Needle Through a Balloon

Demo: FM-A-NB
Pira Index: 2B 30.00

Lab Equipment  Directions
  1. balloon
  2. knitting needle
  3. base to hold needle
  4. vaseline
  1. Blow up the balloon.
  2. Lubricate the point of the needle with vaseline and slowly insert it into the inlet or neck of the balloon where the rubber is slightly thickened. Push the needle on into the balloon and through the thickened part on the opposite side.

You may need to lubricate both ends of the balloon as well. Practice is recommended.


Demo: FM-C-WB
Pira Index: 2C 20.00

 Lab Equipment  Directions
  1.  windbag
  1.  Stretch the windbag across the floor and ask a student to attempt to blow it up with just one breath.
  2. After he/she has little success, cup your hand loosely around the neck of the bag and staying about 6″ from the opening quickly blow towards it quickly closing the bag to trap the air that rushed into it.


Venturi Floating Balls

Demo: FM-C-VF
Pira Index: 2C 20.10

 Lab Equipment  Directions
  1.  Venturi tube
  2. 3 ping pong balls
  3. Pasco air pump (with hose that has tape on the end)
  1.  Set up the apparatus as shown.
  2. Connect air to open end of venturi tube.
  3. Turn on the pump and position a ball above each of the three upward air flow tubes.
  4. Note that the center ball equilibrates at a lower level than the other two.

Vortex Cannon

Demo: FM-C-VC
Pira Index: 2C 50.15

 Lab Equipment  Directions
  1.  vortex cannon with laser
  2. clear plastic container
  3. candle on holder
  4. mylar balloon
  5. paper screen
  6. matches
  1. fog machine
  2. video encyclopedia of physics
  1.  Use rubber band to turn laser on and stick it to velcro on side of cannon.
  2. Set one of the two targets 3-10 feet away.
  3. Use the laser to point to target next to a wall or in front of the paper screen.
  4. Hit diaphragm on the cannon with the clear plastic container while aiming at the target.


Terminal Velocity

Demo: FM-C-TV
Pira Index: 2C 30.50

 Lab Equipment  Directions
  1.  2 graduated cylinders
  2. 2 glass marbles
  3. plastic slide with two openings
  4. bottle of salt
  1.  Fill both cylinders with water.
  2. Add a moderate amount of salt to one of the cylinders.
  3. Place the plastic plate on top of the cylinders as shown.
  4. Slide plastic plate as shown to create opening to drop marbles.
  5. Note the difference in the velocity of the two marbles.
  6. Retrieve the marbles.
  7. Repeat steps 1-5, but add salt salt to one of the cylinders until saturation is reached.