# Homework Help: Modelling Air Resistance using Differential Equation

1. Mar 5, 2005

### $id hi , As a part of my project, i am modelling air resistance using a differential equation. For the write up, i need to discuss what assumptions i am making. I have the rest of the coursework sorted out. I have a few idea . Air resistance is presumed to be consistent. ( i.e no pressure changes) There are no drafts or breezes in the experimental setup. Any others? sid 2. Mar 5, 2005 ### dextercioby What are your ideas...? Daniel. 3. Mar 5, 2005 ###$id

well i have posted some of ideas already but i was wondering what would be the main sources of errors and assumptions of dropping some paper cups to measure air resistance constant.

4. Mar 5, 2005

### dextercioby

You wish to set up a diff.equation.That's okay.There are 2 types of friction forces involved:Stokes type (viscous fluid,small velocities) and drag forces (big velocities)...

So choose the exact type of model (gravity,velocity range) and then set up the diff.eq.

Daniel.

5. Mar 5, 2005

### xanthym

"Air Resistance" (or "Aerodynamic Drag") has been studied extensively. There are several different physical phenomena involved, and the dominant factors are generally indicated by the Reynold's Number value(s) for the experiment. Reynold's Number usually provides indication of the turbulence regime and drag characteristics, and thus the general approaches you can take in studying your problem. Parameters like Drag Coefficient are usually involved in formulating the basic equations. The URLs below discuss these concepts and should help formulate your approach. (Most involve a series of tutorial pages.)
http://www.lerc.nasa.gov/WWW/K-12/airplane/falling.html [Broken]