Will a falling object minimize air drag?

In summary, an object falling near the surface of the Earth will experience a drag force from air molecules. Whether or not the object will fall in a way to minimize air drag depends on its shape and mass distribution. There is a possibility of the object ending up in a stable configuration or continuing to tumble. This can be seen in real world examples, such as when jets flame out and go into a flat spin, which is both stable and has high drag. The shape of the object also plays a role, as a relatively orientation-independent center of pressure will lead to the center of mass eventually being below it. This is seen in the example of a "flat penny" falling from a skyscraper, which is discussed in the article referenced.
  • #1
skazis
8
0
Hi,

An object is falling near the surface of the Earth. We assume there is a drag force acting on it due to the air molecules. It's initial conditions are such that it rotates and is in a chaotic motion.
Will the object will fall in the end in such a way to minimize air drag? And if yes - how can it be explained? I was thinking of least action principle as smaller drag force will make sure object reaches surface sooner.
 
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  • #2
Nope - it may end up in a stable configuration (which is not necessarily, or even often, the least drag configuration), or it may continue tumbling. It mainly depends on the shape of the object and its mass distribution. Specifically, if the object has a relatively orientation-independent center of pressure, it will eventually end up with the center of mass below the center of pressure.
 
  • #3
cjl said:
Nope - it may end up in a stable configuration (which is not necessarily, or even often, the least drag configuration), or it may continue tumbling. It mainly depends on the shape of the object and its mass distribution. Specifically, if the object has a relatively orientation-independent center of pressure, it will eventually end up with the center of mass below the center of pressure.

A real world example: this happens often - and with lethal results - when jets flame out and go into a flat spin.

The flat spin is quite stable (the pilot is unable to escape from it), but at the same time is the highest drag configuration.
 
  • #5


I can provide a response to this question by explaining the principles of air drag and the motion of falling objects.

Firstly, air drag is a force that acts on objects as they move through a fluid, such as air. This force is caused by the resistance of the fluid molecules to the motion of the object. As an object falls, it experiences an upward force of air drag that opposes its downward motion.

In terms of minimizing air drag, it is important to understand that the drag force is dependent on the velocity of the falling object. As the object falls, its velocity increases, causing the drag force to also increase. However, at a certain point, the drag force reaches a maximum value and then begins to decrease. This is known as terminal velocity, and it occurs when the drag force equals the force of gravity on the object.

So, to answer the question, yes, a falling object will eventually minimize air drag and reach terminal velocity. This is because the object's motion is governed by the laws of physics, specifically the principle of least action. This principle states that a system will always take the path of least resistance or least energy expenditure. In the case of a falling object, the path of least resistance is reaching terminal velocity, where the drag force is at its minimum.

In terms of explaining how this happens, we can look at the chaotic motion mentioned in the question. As the object falls, it may initially have a chaotic motion due to external forces or its shape. However, as it reaches higher velocities, the drag force becomes the dominant force, and the object's motion becomes more streamlined and stable. This allows the object to reach terminal velocity and minimize air drag.

In conclusion, a falling object will eventually minimize air drag and reach terminal velocity due to the principle of least action. This can be explained by the relationship between velocity and drag force, as well as the object's motion becoming more streamlined at higher velocities.
 

What is drag force in a free fall?

Drag force in a free fall is the force exerted on an object in motion through a fluid (such as air) that opposes the motion of the object. It is caused by the object pushing against the fluid particles, resulting in a force that acts in the opposite direction of the object's motion.

How is drag force calculated?

Drag force can be calculated using the formula F = 1/2 * ρ * v^2 * A * Cd, where ρ is the density of the fluid, v is the velocity of the object, A is the cross-sectional area of the object, and Cd is the drag coefficient. This formula takes into account the object's shape, size, and speed to determine the force of drag acting on it.

What factors affect the drag force on an object in free fall?

The drag force on an object in free fall is affected by several factors, including the object's shape, size, speed, and the density and viscosity of the fluid it is falling through. Additionally, the roughness of the object's surface and the presence of any external factors, such as wind or turbulence, can also impact the drag force.

How does drag force affect the motion of an object in free fall?

The presence of drag force in a free fall can significantly impact the motion of an object. As the drag force increases, it can slow down the object's acceleration and decrease its terminal velocity (the maximum speed it can reach in free fall). This is because the drag force acts in the opposite direction of the object's motion, causing it to experience air resistance and ultimately fall at a slower speed.

Can drag force be completely eliminated in a free fall?

No, it is not possible to completely eliminate drag force in a free fall. Even objects with a streamlined shape and minimal surface area will still experience some drag force as they fall through a fluid. However, the amount of drag force can be reduced by optimizing the object's shape and minimizing its surface area, allowing it to fall at a faster velocity.

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