Example of kinetic force > static force

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Discussion Overview

The discussion revolves around the question of whether there are scenarios where kinetic force exceeds static force, particularly in the context of friction. Participants explore examples and clarify concepts related to static and kinetic friction, as well as other forces.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant asks for examples where kinetic force is greater than static force.
  • Another participant mentions that any object traveling faster than 0.866c has kinetic energy greater than its rest energy, suggesting a possible interpretation of kinetic force.
  • A participant explains that static force, such as friction, exists regardless of motion, while kinetic force, like drag, only applies to moving objects, indicating that the relationship between the two depends on the situation.
  • One participant provides various definitions of static force, including friction, tensile strength, shear strength, and gravity, and gives examples like a skateboard going downhill and scissors cutting paper.
  • A participant rephrases their question to specifically seek examples where kinetic friction exceeds static friction.
  • Another participant expresses uncertainty about solids exhibiting this behavior, noting that static and kinetic friction can be similar in some cases, such as teflon on teflon.
  • There is mention of control mechanisms like slide rails that utilize fluid to manage resistance, although this does not directly relate to static versus dynamic friction.

Areas of Agreement / Disagreement

Participants do not reach a consensus on whether kinetic friction can exceed static friction, and multiple viewpoints on the definitions and examples of forces remain present throughout the discussion.

Contextual Notes

Some participants express uncertainty about the specific conditions under which kinetic and static forces are compared, and there are references to coefficients of friction that may vary based on materials and situations.

PCSL
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Can someone give me an example of a case where kinetic force would be greater than static force? Thanks.
 
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Any object traveling faster than 0.866c will possesses kinetic energy greater than it's own rest energy (if this is what is meant btw).
 
If I understand your question correctly then friction would be an example of a static force. It exists regardless of whether an object is moving or not. Drag would be an example of a kinetic force. It is only experienced by objects that are moving through a fluid or gas. As to whether one is greater than the other that depends on the situation.
 
Can someone give me an example of a case where kinetic force would be greater than static force? Thanks

I expect you are referring to impact forces.
 
In general a static force is a resistance between two forces.

static force = mass
inottoe said:
Any object traveling faster than 0.866c will possesses kinetic energy greater than it's own rest energy (if this is what is meant btw).

static force = friction
Skateboard going down hill.

static force = tensile strength
A weight that breaks a rope used to suspend it.

static force = shear strength
Scissors cutting paper.

static force = gravity
An airplane in flight.
 
I'm an idiot, I apologize. I meant friction.

So to rephrase my question: Can someone please provide an example where kinetic friction > static friction.
 
PCSL said:
Can someone please provide an example where kinetic friction > static friction.
I'm not aware of any solids that have this behavior, although the static and kinetic friction can be close for some cases, like teflon on teflon, with a coefficient of about 0.4 for both.

There are control mechanisms called slide rails that use a fluid between the rail and a slider. The presence of the fluid results in resistance to movement that increases with speed, to elminate jerky movements for precise control. Some of these maintain the fluid by pumping the fluid through holes in the rail. This isn't really a case of static versus dynamic friction though.
 
rcgldr said:
I'm not aware of any solids that have this behavior, although the static and kinetic friction can be close for some cases, like teflon on teflon, with a coefficient of about 0.4 for both.

There are control mechanisms called slide rails that use a fluid between the rail and a slider. The presence of the fluid results in resistance to movement that increases with speed, to elminate jerky movements for precise control. Some of these maintain the fluid by pumping the fluid through holes in the rail. This isn't really a case of static versus dynamic friction though.

Thank you.
 

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