Air resistance on a rotating cylinder

[Hajk]

Hi, I have an object that's rotating in the air with constant speed. Now a bit simplified it could be looked as an uniform cylinder that's rotating round and round (not like a propeller). How would air resistance affect this rotation and how could you describe this force with a formula?

Thanks

 

[rcgldr]

Friction and viscosity would cause the air to circulate in the vicinty of the cylinder, with the air's velocity decreasing with distance from the suface of the cylinder. The air's resitance to this would create an opposing drag torque on the cylinder.

 

[astrokreng]

for your question! Air resistance can definitely play a role in the rotation of an object, especially if it is rotating at a high speed. The air resistance force, also known as drag, acts in the opposite direction of the motion of the object and is caused by the friction between the object and the air molecules it encounters.

In the case of a rotating cylinder, air resistance would act on the surface of the cylinder as it moves through the air. This would create a force that opposes the direction of rotation, causing the cylinder to slow down. The magnitude of this force is dependent on several factors, including the speed of rotation, the surface area of the cylinder, and the density of the air.

To describe this force with a formula, we can use the drag equation: F = 1/2 * p * v^2 * A * Cd, where F is the drag force, p is the density of the air, v is the velocity of the cylinder, A is the surface area of the cylinder, and Cd is the drag coefficient which takes into account the shape and texture of the object's surface.

It is worth noting that the drag force will increase as the speed of rotation increases, eventually reaching a point where it equals the force of the object's rotation, causing it to reach a constant speed. This is known as terminal velocity.

In conclusion, air resistance can have a significant impact on the rotation of an object, and can be described using the drag equation. It is an important factor to consider when studying the motion of rotating objects in the air.