What happens when two spinning cylinders come in contact?

In summary: The individual cylinders can be treated as subsystems, but the system of both subsystems is not closed. You would need to include the forces applied to the axles in the system, but they are not given.
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thephysicist
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Member warned about lack of posting template.
If two spinning cylinders with different MoIs and angular speeds and different radii come in contact with each other at the curved surfaces, how to find out the final angular speeds given all initial parameters?

There will be a friction acting at the line of contact and perpendicular to it as long as the liner speeds of the surfaces differ. However once they are equal, there will be no friction.

I can work it out by taking the angular impulse of friction on individual cylinders. But my question is, can we apply the conservation of angular momentum? I tried that but the expression differs than the one worked out considering the angular impulse of the friction. Please help.
 
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In PF the use of the template is mandatory. Gives you an opportunity to tell us which way the things are running: that makes a considerable difference!

And what are Mols of a centrifuge ?
 
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thephysicist said:
can we apply the conservation of angular momentum?
No. The cylinders (though this is not clearly stated) are presumably mounted on axles, which are held fixed. That implies external forces applied to the system. Since there are two axles, there is no reference point you can use for the angular momentum that will eliminate both forces.
 

FAQ: What happens when two spinning cylinders come in contact?

1. What causes the cylinders to spin?

The cylinders are initially set in motion by an external force, such as a person pushing them or a motor rotating them. Once in motion, the spinning motion will continue due to the law of inertia, which states that an object in motion will stay in motion unless acted upon by an external force.

2. What happens when the cylinders come in contact?

When the cylinders come in contact, their surfaces will experience frictional forces. This friction will cause the cylinders to slow down and eventually stop spinning.

3. Will the direction of rotation change when the cylinders collide?

The direction of rotation may change when the cylinders collide, depending on the angle of contact and the relative speeds of the cylinders. If the cylinders collide head-on with equal speeds, their direction of rotation will remain the same. However, if they collide at an angle or with different speeds, their direction of rotation may change.

4. Are there any other factors that affect what happens when the cylinders come in contact?

Yes, there are other factors that can affect what happens when the cylinders come in contact. These include the surface materials of the cylinders, the amount of force applied, and the presence of any lubricants or contaminants on the surfaces.

5. Can the cylinders continue spinning after coming in contact?

In most cases, the cylinders will not continue spinning after coming in contact due to the frictional forces between their surfaces. However, if the cylinders are made of very smooth and low-friction materials, and there is minimal force or contact between them, they may continue spinning for a short period before eventually slowing down and stopping.

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