Maximum possible static friction

In summary: It is up to you, the reader and engineer, to figure out that the static frictional force is the minimum amount required to move an object. In summary, the maximum possible static friction between a body and a surface can be either equal to or less than the product of the coefficient of static friction and the normal force. When the applied force on the object is greater than the maximum static friction, the object will start moving. However, if the applied force is equal to the maximum static friction, the object will not move, but a small increase in the applied force will cause the object to accelerate. This can sometimes lead to confusion, as some sources may not mention this distinction between the maximum static friction and the minimum force required to start
  • #1
boris16
46
0
hi

Is maximum possible static friction between a particular body and a particular surface equal or smaller to k(s) * N ?

k(s) means coefficient of static friction

If it is smaller, then only when force pulling on object is greater than C(s)*N will body start moving ?


I'm confused since I found few articles on the net saying max_possible_stat_fric < k(s) * N, while others even saying max_possible_stat_fric equals k(s) * N and yet at the same time claiming when both the pulling force and max_possible_stat_fric are equal to k(s) * N the object starts moving, which doesn't make sense since the two forces would cancel each other out

thanx
 
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  • #2
The force of static friction is less than or equal to (coefficient of s. friction)x(normal force). The maximim possible is equal to "k(s)*N" (as you put it.

The reason why static friction can be less, is due to the fact that if nothing is pushing on a stationary object, there is no frictional force at all on it. If a small applied force is put on the object, and the object does not move, then the static friction only has to be enough to balance the small applied force.

If an applied force that exactly equals the max static friction is on an object, technically forces are balanced and the object does not move; but if this applied force is infinitessimally larger, then the object will accelerate. Let's say the maximum static frictional force is 25 N. An object will begin to accelerate if you apply a force of 25.0000000001 N. This is why they say that the "minimum force required to start the motion is equal to the maximum static frictional force." Rounding to significant digits, 25.000000000001 equals 25.
 
Last edited:
  • #3
thank you. It's strange tho that they wouldn't mention that since it can confuse a person
 
  • #4
"They" do this all the time.
 

1. What is maximum possible static friction?

Maximum possible static friction is the maximum amount of force that can be exerted between two surfaces before they start to slide against each other. It is dependent on factors such as the type of materials, surface roughness, and the normal force applied.

2. How is maximum possible static friction different from kinetic friction?

Maximum possible static friction is the force that must be overcome to set an object in motion, while kinetic friction is the force that opposes the motion of an object already in motion. Maximum possible static friction is typically higher than kinetic friction.

3. How is maximum possible static friction calculated?

The maximum possible static friction is calculated by multiplying the coefficient of static friction, which is a material property, by the normal force applied between the two surfaces. This gives the maximum force that can be applied before the object starts to slide.

4. What factors affect the maximum possible static friction?

The maximum possible static friction is affected by the type of materials in contact, the surface roughness, and the normal force applied. Additionally, the coefficient of static friction can vary with temperature and surface conditions.

5. Why is maximum possible static friction important?

Maximum possible static friction is important in many practical applications, such as designing brakes for vehicles and ensuring objects do not slip or slide during transportation. It also helps us understand the behavior of objects at rest and in motion, and how different materials interact with each other.

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