Friction between two faces of rotating cylinders

In summary, there are two cylinders, one rotating with initial angular velocity and the other placed on top with no initial angular velocity. The faces of the cylinders have a coefficient of friction. The question at hand is determining the equation for energy lost due to friction in this rotational setup, with the clarification that the curved surfaces are not in contact. The suggested equation is U_f = mu*Int(T*d(theta)), with T representing the tangential force between the two cylinders.
  • #1
jeanius
11
0

Homework Statement


A rotating flywheel with radius r is spinning with initial angular velocity 'w' and has moment of inertia 'Ic' whose axis of rotation is in the vertical direction. Another cylinder is placed on top of it with no initial angular velocity, radius r, and moment of inertia 5*Ic. The two cylinders' faces have coefficient of friction 'mu'. Eventually, the cylinders both rotate without slip as one.

Homework Equations


I'm trying to determine the equation for the energy lost due to friction. I have a handle on the rest of the equation (conservation of momentum, energy balance), but I'm having trouble adapting the typical linear equation for friction energy (U_f = mu*Int(F_normal*dx)) to a rotational setup. Would the dx in the previous equation become r*dr*d(theta), in which theta is the amount of rotation traversed before no slip?

Clarification: the curved surfaces are not in contact with each other, but the top faces such that the axes of rotation are not just parallel but coincident.

The Attempt at a Solution

 
Last edited:
Physics news on Phys.org
  • #2
I'm assuming that since the two cylinders are in contact, the equation for energy loss due to friction would be U_f = mu*Int(T*d(theta)), with T being the tangential force between the two cylinders. Is this correct?
 

FAQ: Friction between two faces of rotating cylinders

1. What causes friction between two faces of rotating cylinders?

Friction between two faces of rotating cylinders is caused by the resistance between the two surfaces as they slide or roll against each other. This resistance is due to the microscopic roughness of the surfaces and the intermolecular forces between them.

2. How does the friction affect the rotation of the cylinders?

The friction between the two faces of rotating cylinders can slow down or even stop the rotation of the cylinders as it converts the kinetic energy of the rotation into heat energy. This can also result in wear and tear on the surfaces of the cylinders.

3. Can the amount of friction between the cylinders be reduced?

Yes, the amount of friction between the cylinders can be reduced by using lubricants between the surfaces or by using materials with lower coefficients of friction. Additionally, ensuring the surfaces are smooth and free of debris can also reduce friction.

4. How does the speed of rotation affect the friction between the cylinders?

The speed of rotation can affect the friction between the cylinders as higher speeds can generate more heat and wear on the surfaces, resulting in increased friction. However, at very low speeds, the friction can also increase due to the surfaces being in closer contact with each other for longer periods of time.

5. Is friction between two faces of rotating cylinders always undesirable?

No, friction between two faces of rotating cylinders can be both desirable and undesirable depending on the situation. For example, in engines and machines, some amount of friction is necessary for proper functioning, but in other cases, friction can cause undesirable effects such as heat and wear on the surfaces.

Similar threads

Kinetic Energy of a Cylinder Rolling Without Slipping
Replies
21
Views
2K
Frictional force between two rotating cylinders
Replies
11
Views
2K
A cylinder of snow rolls down a hill gathering more snow -- calculate its speed
2
Replies
39
Views
2K
How Does Adding Masses Affect the Angular Velocity of a Rotating Cylinder?
Replies
12
Views
2K
I Solving Wheel Coming to a Stop: FBD, Friction & Hysteresis
Replies
22
Views
2K
Engineering How Does Cup Anemometer Design Utilize Fluid Mechanics Principles?
Replies
4
Views
1K
I A rod that falls while rotating from the end of a table
Replies
2
Views
329
Motion of Rolling Cylinder in Fixed Cylinder: Confusing Constraint Condition
Replies
2
Views
2K
Two cylinders rotating with contact at an angle (reformulation of the problem)
Replies
6
Views
2K
Cylinder rolling on a moving board
Replies
16
Views
2K

Hot Threads

Recent Insights

Back
Top