Air Resistance Formula: Basics & Explanation

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Discussion Overview

The discussion revolves around the concept of air resistance, also known as drag, including its basic principles, formulas, and applications in physics. Participants explore the complexities of calculating drag, particularly in relation to different speeds and conditions, and share inquiries about conducting experiments related to air resistance.

Discussion Character

  • Exploratory
  • Technical explanation
  • Homework-related
  • Debate/contested

Main Points Raised

  • Some participants describe air resistance as drag and provide the formula for calculating drag, which includes variables such as drag coefficient, air density, projected area, and relative velocity.
  • One participant notes that the drag force acts opposite to the direction of motion, complicating the calculations and suggesting the need for differential equations to determine motion paths.
  • Another participant mentions that drag calculations are simpler when assuming incompressible air but become more complex at high speeds (above 220 mph) due to compressibility effects.
  • A new participant expresses a desire to learn more about movement under air resistance and seeks clarification on the difference between drag and air resistance.
  • One participant shares their experience of preparing for a school project on drag and seeks advice on conducting tests and structuring their written work.
  • Another participant points out that drag is proportional to the square of velocity and discusses the need to demonstrate this relationship in their tests.

Areas of Agreement / Disagreement

Participants express varying levels of understanding and interest in the topic, with some agreeing on the basic principles of drag while others seek clarification on specific aspects. The discussion remains unresolved regarding the precise definitions and distinctions between drag and air resistance.

Contextual Notes

Some participants mention limitations in their understanding of technical terms and concepts, indicating a need for further clarification and exploration of the topic.

Who May Find This Useful

Students studying physics, particularly those interested in fluid dynamics, air resistance, and experimental methods related to drag.

dav2008
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Hm..well I am taking a Physics B course and we never covered the topic of air resistance..
So I was a little curious, so could anyone please give a brief explanation of the basics..or maybe some formula..

I was just wondering if it was really simple like the boyency force or something or really complicated and that's why they didnt teach it to us..
Tx
 
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Air resistance is drag. The calculation for drag is

D=(Cd*A*R*v^2)/2

Cd = is the drag coefficient and it is obtainable from wind tunnel testing data based on the shape of the object, and the reynolds number.

R is the air density, which can be calculated or taken from charts

A is the projected area normal to the flow

v is relative velocity
 
The thing which makes it tricky is that the drag acts in the direction opposite the motion at each point in time.

That means that you don't have a simple formula to plug and chug. You need to look at the differential equations and (for most if not all cases) do step derivations to find the path.

If you're familiar with differential equations and interested, I'll go into a little more detail.
 
Thanks for the info!

Yea, that's what i was looking for...Im not taking calc yet...Going to take that next year.

I just wanted a general idea what the air resistance was all about
 
Drag is pretty easy when you consider air to be incompressible, but above about 220 mph you must consider the compressibility and the calculations are more complicated.
 
hi there, I'm new (you see ;) ) and would like to know more about movement under air resistance or how its called (drag-movement?)... I'm from germany and do understand english, but not perfect...
i have already some information about drag, but would be pleased if you could give me more information, not only about drag, but also about movement under air resistance... to be more specific i do not really need much infos about "more than 220mph" (balistic or how its called) but would be nice to read also some of it... hope you understand me?!
 
Hi TeT,

Welcome to the forums.

The topic of drag and air resistance is pretty large. Could you be a little more specific as to what you're trying to find out about?
 
hmm more specific? i will try...
the situation is as follows: i have the task (as far as i know jet) about "movement under air-resistance" (or drag-motion or so (in german called "bewegung mit luftwiderstand")) and what I've done till now is to collect all information i could find about air-resistance... but always when i want to know more i get into another "topic" like air-planes, or balistic (bullets)... and as we have holidays now here in germany i don't knot what exactly my teacher want me to study about, so I'm waiting for some emails to be answered... furthermore i will do some test in school for showing drag, and that's (i think) the point, because when i record the test with a camera and do a report about the tests with some pictures in it, i think there will be no more place in the guideline of about 15 pages with given font and size of it, to talk much about drag by/of air-planes or so... so i think i should stay near my tests i will do... the tests are ... hmm how do i explain: we have i kind of "hover-board" in school ("luftkissenbahn" google says "air cushion course") with a plate on it for showing the drag... i don't know how to explain, but first o would like to know how to do some tests about drag... i have seen some on the internet, but our school do have have that "thing" with tells you the "Cd" (the picture below show the "thing" i mean), but nevertheless i think we have enough stuff in school to do some tests, so you could help me if you have any idea of doing a test or tell me with parts i MUST incude in my written work... (like to start with some deffinition of drag...)
hope you understand me, if not, tell me and i will try to explain in a different way... thanks for the replys ;)

edit: damn i can't see the attached pic? why?
 

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1. question: what is the difference of drag and air-resistance? thougt its the same thing, but as enigma worte:

>The topic of drag AND air resistance is pretty large...

i'm not sure
 
  • #10
yeah i already found out that the drag is proportional to velocity squared and the (hmm german: "leistung" = achievement ?) is proportional to velocity*e3... and as i know i should show the proportional to velocity squared, so the tests will need a certain speed...
hmm so much new words in here, i think i have to learn first all the terms i need in english...

ps. thanks for replys so far... seems to be a great board (where you can find quick help...)
 

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