-friction Is Independant Of Surface Area-

In summary: This is why sliding loses energy while rolling.thank u sir,In summary, rolling is better than sliding because in rolling, friction merely CONVERTS translational kinetic energy into rotational energy without net energy loss, whereas in sliding, the object loses kinetic energy.
  • #1
arunk8186
7
0
----friction Is Independant Of Surface Area------

>> can anyone tel y friction is independant of surface area/length ...

thx an regards,

arun
 
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  • #3
thank u sir ...to rephrase my question to get a still better explnation (wit regard to myself) ...

>> why is rolling better than sliding ??

thx and regards,

arun
 
  • #4
Rolling is better than sliding, because in rolling, friction merely CONVERTS translational kinetic energy into rotational energy without net energy loss, wheres in sliding, the object loses kinetic energy.
 
  • #5
thank u sir,
my question is why does while sliding ,kinetic energy is lost as (friction) heat energy...why not while rollin?

thanks and regards,

arun
 
  • #6
Let S be a system of N particles, and let [itex]\vec{F}_{i}[/itex] be the net force acting upon the i'th particle.
The system's S rate of change of kinetic energy equals the sum of the particles' rates of change of kinetic energy.
Thus, if [itex]K_{i}[/itex] is the kinetic energy of the i'th particle, the rate of change is:
[tex]\frac{dK_{i}}{dt}=\frac{d}{dt}(\frac{m_{i}\vec{v}_{i}^{2}}{2})=m_{i}\vec{a}_{i}\cdot\vec{v}_{i}=\vec{F}_{i}\cdot\vec{v}_{i}[/tex]
where [itex]\vec{v}_{i},\vec{a}_{i},m_{i}[/itex] is the i'th particle's velocity, acceleration and mass, respectively.

Now, the frictional force acting upon an object (or system S) acts upon the the "particle" directly in contact with the ground. Since the particle at the contact point is MOMENTARILY AT REST, its velocity is 0, and hence, the frictional force acting upon it cannot change its OR THE REST OF THE SYSTEM's kinetic energy! Otherwise stated, in rolling, friction does NO WORK.

In sliding, however, the particle at the contact point has a non-zero velocity, and hence, the friction force does non-zero work on the particle, and hence on the system as well.
 

1. What is friction and how is it related to surface area?

Friction is the force that resists the motion of two surfaces when they are in contact with each other. It is related to surface area because the larger the surface area in contact, the more friction there will be.

2. Is friction always dependent on surface area?

No, friction can also be affected by other factors such as the nature of the materials in contact, the force pressing the surfaces together, and the roughness of the surfaces.

3. Why is friction independent of surface area?

Friction is independent of surface area because it is a result of the molecular interactions between the two surfaces, not the overall size or shape of the surfaces.

4. How does surface area affect the coefficient of friction?

Surface area does not directly affect the coefficient of friction. The coefficient of friction is a constant value determined by the nature of the surfaces in contact and the other factors mentioned earlier.

5. What are some real-world examples of friction being independent of surface area?

One example is the friction between a car tire and the road surface. The amount of surface area in contact between the two does not significantly change the amount of friction, as the coefficient of friction is mainly determined by the materials and conditions of the road and tire. Another example is the friction between two pieces of paper, which remains relatively constant regardless of the size or shape of the paper.

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