Understanding the Drag Equation

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In summary, the conversation discussed the individual's interest in understanding air resistance and their recent decision to learn about the formulas that model its behavior. They specifically mentioned the drag equation and how it seemed like a useful tool, but they wanted to understand its origins. They referenced NASA's website and a specific link for more information. They also mentioned their understanding of the first step in the derivation of the drag equation, which involves Newton's laws and linear momentum. They were not as familiar with the second step, but they understood the concept of determining the amount of fluid a body will collide with based on its velocity and contact surface area. They had a question about why the velocity (V) in the first formula was the same as the velocity (V)
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DarkFalz
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For several years i have thought about air (fluid) resistance without getting deeper into the formulas that model its behaviour. Recently, I've decided to take one more step in the subject and learn some of these formulas.

I've learned about the drag equation, and at first glance it seemed like a "pretty" formula, which could answer my questions regarding air resistance in everyday affairs.

Yet, i have decided to try to understand it and its origins, and so i took a look at NASA's website and checked this link https://www.grc.nasa.gov/www/k-12/airplane/momntm.html

I don't know if i am correctly understanding the several steps involved in the derivation of the drag equation. I am familiar with Newton's laws and the concept of linear momentum, so i think i understand the first step. It is saying that if a body when moving through a fluid causes its momentum to change from 0 to m*v over a given amount of time T, then a force with average value m*v / T acted upon the moving body throught the period of time T, right?

I am not that much familiar with the second step, but i think i get the point, basically they're determining the amount of the fluid that the body will colide with if it is moving through the fluid with velocity V and has a contact surface A with the fluid.

The point that i am missing, is why the V involved in the first formula (m*V / T), which i assume is the velocity of the fluid, is the same V from the mdot equation, which is related to the velocity of the body passing through the fluid, or so did understand understand.

Thanks for the attention
 
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DarkFalz said:
why the V involved in the first formula (m*V / T), which i assume is the velocity of the fluid, is the same V from the mdot equation, which is related to the velocity of the body passing through the fluid
It's the relative velocity between body and fluid.
 

What is the drag equation and why is it important?

The drag equation is a mathematical equation used to calculate the drag force on an object moving through a fluid, such as air or water. It is important because it helps us understand and predict the amount of resistance an object will experience as it moves through a fluid, which is crucial in various fields such as aerodynamics, hydrodynamics, and vehicle design.

What are the components of the drag equation?

The drag equation includes four components: the drag coefficient, the fluid density, the velocity of the object, and the reference area. These factors all play a role in determining the amount of drag force experienced by an object.

How is the drag coefficient determined?

The drag coefficient is a dimensionless value that represents the level of drag on an object. It is determined through experimental testing and can vary depending on factors such as the shape and surface roughness of the object, as well as the fluid properties and flow conditions.

What is the relationship between velocity and drag force?

The drag force increases with an increase in velocity, as stated by the drag equation. This means that as an object moves faster through a fluid, it will experience more resistance and a higher drag force.

Can the drag equation be applied to all types of objects moving through fluids?

The drag equation can be applied to a wide range of objects, as long as they are moving through a fluid. However, it may not accurately predict the drag force for very complex or highly non-uniform shapes, and in these cases, more advanced equations may be needed.

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