MadSci Network: Physics

Re: What demos on viscosity would be best to present to my class? (simple)

Date: Tue May 8 11:09:59 2001
Posted By: Steve Williams, Staff, Science Demonstrator, Pacific Science Center
Area of science: Physics
ID: 988256381.Ph

Hi Michelle!

Viscosity is a cool subject, though it can be difficult to convey to people 
without resorting to long descriptions. I'll leave the describing to you, 
and offer you these suggestions for demonstrations:

The maple syrup race:
Maple syrup is much more viscous than water, and you can show this by 
pouring some water and some maple syrup down an inclined plane.

The marble race:
Take a couple of graduated cylinders, and pour into one some water (or baby 
oil) and the other karo (corn) syrup. Drop a marble into each. The 
difference in speeds is slight, but noticable. If you have access to longer 
cylinders, even better, as this demonstration is aided by long falls.

Temperature dependent viscosity:
Take some melted candle wax and pour it into a jar. Note it's low viscosity 
and it's other flow properties while hot. Let cool slightly and pour it 
into another jar. Note the decrease in temperature causes an increase in 
viscosity. Repeat until it hardens.

The volcano:
Volcanoes act the way they do because of the different viscosities of the 
magma within them. Hawaiian volcanoes have less viscous lava than volcanoes 
in Washington State, and because of this they act differently. Hawaiian 
volcanoes erupt often, giving off large amounts of material that slowly 
flows out and forms a broad shield. Washington State volcanoes erupt 
infrequently, with great force, throwing huge amounts of material into the 
air and surrounding areas. This is because the material is so viscous, it 
allows tremendous pressures to build up before eruption, increasing the 
force of the eruption.
Here's how to demonstrate this: Take two squeeze bottles (the squeezier the 
better -- I first did this with a full and empty toothpaste tube!) and fill 
one bottle with water, and the other with a viscous susbtance like Karo 
Syrup. Squeeze gently on the water bottle and observe how the water flows 
out with very little force. Squeeze the Karo Syrup bottle and note how 
difficult it is to make it flow upward. Now squeeze super hard and it will 
come out of the tube -- it required much more force to do it!
The reason I like to do this with toothpaste tubes is simple: for my 
viscous substance, I use toothpaste! The other I fill with water (Note that 
this takes a little time and patience). Squeezing the water one causes an 
easy flow, a low viscosity action. Squeezing the toothpaste with equal 
force causes no flow, so you have to squeeze MUCH harder to get an 

I hope this helps your project!

Take Care and Be Safe,
Steve E. Williams
Rock Star and Science Demonstrator
Pacific Science Center, Seattle, Washington, USA

Current Queue | Current Queue for Physics | Physics archives

Try the links in the MadSci Library for more information on Physics.

MadSci Home | Information | Search | Random Knowledge Generator | MadSci Archives | Mad Library | MAD Labs | MAD FAQs | Ask a ? | Join Us! | Help Support MadSci

MadSci Network,
© 1995-2001. All rights reserved.