Rolling Friction: Static, Kinetic, or Rolling?

In summary, when an object is rolling without slipping, it experiences static friction. If it is rotating and translating without rolling, it experiences kinetic friction. If a rolling body is kept on a surface with constant friction, the friction force will vary with changing angular velocity and is still given by f = k * Normal reaction, where k is the coefficient of friction and Normal reaction is the normal force (in this case, mg). However, if the rolling object is slipping, the friction force may not follow this equation.
  • #1
sArGe99
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When an object is said to be under pure rolling, what friction does it experience? Static, kinetic or rolling friction?
If its not rolling but rather just rotating and translating, what friction does it experience?

If a rolling body is kept on a surface of certain friction constant, does the friction force on it vary with changing angular velocity? Is the friction force still given by f = k * Normal reaction, which in the case mentioned is mg?

I appreciate any help.
 
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  • #2
sArGe99 said:
When an object is said to be under pure rolling, what friction does it experience? Static, kinetic or rolling friction?
If by "pure rolling" you mean "rolling without slipping", then it is static friction. I am not sure what "rolling friction" is.
If its not rolling but rather just rotating and translating, what friction does it experience?
Kinetic friction if it rolls with slipping (like a car "laying on the rubber" as it starts moving).

If a rolling body is kept on a surface of certain friction constant, does the friction force on it vary with changing angular velocity?
Yes if it rolls without slipping. The force of static friction will be whatever is necessary to provide the observed linear and angular acceleration.
Is the friction force still given by f = k * Normal reaction, which in the case mentioned is mg?
Yes but only if there is rolling with slipping, i.e. if the instantaneous point of contact on the rolling object is not at rest with respect to the surface on which it rolls.
I appreciate any help.
Good luck.:smile:
 
  • #3


Rolling friction is a type of friction that occurs when an object is rolling on a surface. It is a combination of both static and kinetic friction. When an object is under pure rolling, it experiences a combination of both static and kinetic friction. This is because the point of contact between the object and the surface is stationary, but there is also movement between the two surfaces.

If an object is just rotating and translating, it experiences a combination of kinetic and rolling friction. This is because there is movement between the object and the surface, but the point of contact is also moving.

When a rolling body is kept on a surface with constant friction, the friction force on it does not vary with changing angular velocity. This is because the friction force is still given by the equation f = k * Normal reaction, where k is the coefficient of friction and the normal reaction is equal to the weight of the object (mg in this case). This means that the friction force remains constant regardless of the object's angular velocity.
 

FAQ: Rolling Friction: Static, Kinetic, or Rolling?

1. What is rolling friction?

Rolling friction is a type of friction that occurs when an object rolls over a surface. It is caused by the contact between the object and the surface, and it can be either static or kinetic.

2. What is the difference between static and kinetic rolling friction?

Static rolling friction occurs when an object is at rest and is about to start rolling. Kinetic rolling friction, on the other hand, occurs when an object is already rolling. The force of static rolling friction is greater than that of kinetic rolling friction.

3. How is rolling friction different from other types of friction?

Rolling friction differs from other types of friction because it involves the rotation of an object. Other types of friction, such as sliding friction and fluid friction, involve the movement of an object in a straight line.

4. What factors affect the amount of rolling friction?

The amount of rolling friction is affected by several factors, including the weight and shape of the object, the type and texture of the surface, and the speed at which the object is rolling. Heavier objects and rougher surfaces typically have higher rolling friction.

5. How can rolling friction be reduced?

Rolling friction can be reduced by using smoother surfaces, such as wheels with ball bearings, and by using lubricants to reduce the contact between the object and the surface. Additionally, reducing the weight of the object can also decrease rolling friction.

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