# OCR 2009 Physics Plan

1. Apr 4, 2009

### Monroe

1. The problem statement, all variables and given/known data

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.
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.

2. Relevant equations

Stokes law : F=6πrηv

F= the resistive force experienced by the sphere as it travels through the medium
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 travelling 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

3. The attempt at a solution
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Apr 16, 2009