# Homework Help: Viscosity of liquids

1. Oct 17, 2005

### sueanne

hello, i need to know about the viscosity of liquids i.e. the science behind it. most websites i looked into did not help at all!
also, i am doing an experiment based on the viscosity of liquids and have five liquids to choose from : honey, olive oil, ethanol, water, and corn syrup. please advice me on which liquid to choose from and the scientific reason for it pls thanks
p.s. temperature and terminal velocity are the variables.

2. Oct 17, 2005

### Diane_

Honey, we need a little more information. What do you need to know about viscosity? What causes it? What factors it depends on? Also, what is the experiment about? Why do you have to pick one of those liquids? What are you trying to do with them?

3. Oct 17, 2005

### sueanne

okay, my coursework is based on temperature affecting a liquid when a ball is dropped into it. we have to find out how the temperature affects the terminal velocity of the ball being dropped and the visocity of the liquid. so far, ive explained that at room temperature the visocity of a liquid can be quite high because of the particles being more compact but at higher temperatures the visocity is less, liquid is runnier due to the particles having extra kinetic energy thus able to spread out more. i based this on an example: cooking oil in a pan.

my question is that for my preliminary i have to find out what temperatures and type of liquid to use. ive foudn out that water, ethanol and maybe corn syrup is not good, cause the ball falls too fast. but its better in olive oil and honey. regarding the temperatures, isnt it dangerous to heat up ethanol too high?? like around 65 degrees?

also how can i relate my explanation above to terminal velocity?

4. Oct 17, 2005

### Diane_

OK - first off, I would strongly suggest that you not heat ethanol. It - or, more properly, the vapors it gives off - is highly flammable. It can be heated safely, but I (at least) would be uneasy about you doing it with a large enough sample to drop a ball into.

If I understand you correctly, you're trying to measure the speed at which a ball falls through a viscous liquid as a function of the temperature of the liquid. You're looking for a single liquid to use with as large a difference between its viscosity at low temperatures and at high - is that right? You might look here:

http://www.hypertextbook.com/physics/matter/viscosity/

About a third of the way down that page is a table listing the viscosity for various liquids (and solids and gases, too) at certain temperatures. You might look at corn oil.

Relating your explanation to "terminal velocity": First off, not to be picky, but "terminal speed" would be preferable. Can you see why? Beyond that - what, exactly, is terminal speed? I think the relationship between that and what you're doing is pretty obvious.