Friction for different contacts

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In summary, the conversation discusses the difference between rolling friction and sliding friction and questions why rolling friction is less than sliding friction. It is explained that "rolling friction" is not actually friction but rather a loss of energy due to continual deformation of the wheel. This is known as rolling resistance, which is typically ignored in exam questions. The friction at the point of contact for sliding bodies is dynamic friction, while for rolling bodies it is static friction.
  • #1
sriram123
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Hi all,
I know this is a very basic question and has been discussed in various threads.Anyway i would i like to ask this.

If the value of friction only depends on coefficient of friction and normal force, why is rolling friction less than sliding friction? Is it because the value of Rn the reaction force changes?

I know this is very elementary but I thought it would make my understanding better.

Thanks in advance
 
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  • #2
hi sriram123! :smile:
sriram123 said:
If the value of friction only depends on coefficient of friction and normal force, why is rolling friction less than sliding friction? Is it because the value of Rn the reaction force changes?

"rolling friction" isn't actually friction, it's a loss of energy caused by continual deformation of the wheel where it meets the surface :wink:

from the pf library:
Friction:

Friction at the point of contact of a rolling body is static friction.

There is also a rolling resistance, or "rolling friction": an additional small force, caused by deformation of the body (in exam questions it can usually be ignored).

Friction at the point of contact of a sliding body is of course dynamic friction.​
 

1. What is friction and why does it occur?

Friction is a force that resists the motion of an object when it comes in contact with another object. It occurs because of the microscopic irregularities on the surface of objects, which interlock and create resistance when they slide against each other.

2. How does the type of contact affect friction?

The type of contact between two objects can affect friction in various ways. For example, friction is higher for rough surfaces compared to smooth surfaces, and it is lower for objects with a larger surface area in contact.

3. What factors affect the magnitude of friction?

The magnitude of friction is affected by factors such as the type of surfaces in contact, the force pressing the surfaces together, the speed of the object, and the presence of lubricants.

4. How do we measure friction for different contacts?

Friction can be measured using various methods, such as the inclined plane method, the spring balance method, and the coefficient of friction method. These methods involve measuring the force required to move an object against a surface with known properties.

5. Can friction be reduced or eliminated?

Friction cannot be completely eliminated, but it can be reduced by using lubricants, polishing surfaces, or using materials with low friction coefficients. However, in some cases, friction is necessary for the proper functioning of certain objects.

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