Can You Measure Terminal Velocity in a Classroom Experiment?

[Monroe]

Homework Statement

I am putting forward this plan for discussion, in the hopes that it will be helpful for myself and others also doing this for their ocr physics A A2 levels.

The task is a planning exercise where you must write a plan for the investigation of Stokes' law.
I welcome the addition of new questions to this thread and discussion about this plan.
My particular questions about this, at this time is whether it is possible to measure terminal velocity of a ball baring in a class experiment? The problem i forsee in measuring this, is knowing when terminal velocity is actually reached, and recording this. The ball can be in air or any medium.

Homework Equations

Stokes law : F=6πrηv

F= the resistive force experienced by the sphere as it travels through the medium
r = radius of sphere
η = the coefficient of viscocity of the medium, which can be treated as a constant, unless the temperature or density of the medium changes.
v= the velocity of the sphere

When traveling at terminal velocity, the weight is balanced by the resistive force and upthrust, leading to the equation:

v = kr² where k can be considred as a constant,
such that k = 2(ρs - ρm)g / 9η

where ρs = density of sphere, and ρm = density of medium
g = gravity

The Attempt at a Solution

 

[kiwi3007]

http://www.ugrad.physics.mcgill.ca/labs/Reports/Sample1.htm

great site lots of info and ideas.

and it can really help you get your head around it if you don't get it.