### Re: What is the application for doing a simple project involving viscosity?

Date: Fri Jan 31 22:12:32 2003
Posted By: Nauzad Tantra, Undergraduate, Production/ Industrial engg., D J Sanghvi college of engg.
Area of science: Physics
ID: 1042080159.Ph
Message:

Hi Peter,
Viscosity is a very important parameter in fluids. In most machines using
fluids, a change in viscosity would have disastrous effects on the machine.
Imagine what would happen if the gasoline in your car became as viscous as
grease. The engine wouldnt be able to spray it and as a result the car wont
run.

Coming to your specific question, I cannot think of any practical
application of your experiment. Thats because, the time an object takes to
fall, is not dependant on its density at all. In fact it is only dependant
on the distance it has to travel (s)(which is constant in your case), and
the initial (u) speed and acceleration. The formula to be used is,
s=ut + 0.5 at*t
This does not have any relationship with density.

Now, if you are getting different time intervals for objects of different
densities, it could well be due to the fact that you are using objects
which have different sizes (dimensions).

What you could do is a slight change in plans. You could, using Stokes law
calculate the viscosity of a fluid. Its called the falling sphere
resistance method.

The formula for the experiment is: F = 3*22/7*Mu*U*d

where F is the force acting on the sphere
Mu is the viscosity of the liquid
U is the velocity of the sphere
d is the diameter of the sphere

d can be directly measured using a vernier calliper or a screw gauge (for
more accuracy). U can be measured by noting the time(t) it takes for the
sphere (ball) to fall the entire length (l) of the tube (U=l/t).

F would be the weight of the sphere less the bouyant force.
Bouyant force is the weight of the fluid displaced, which is the volume of
the fluid displaced * the density of the fluid.

Hope this helps. Best of luck