# Friction

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#1
Does friction increase closer to a particle stopping?
E.g. if a particle has driving force 10N and friction 5N, when it stops, will friction be 15N (5 + 10)? Or, is the friction force related to the speed at which it stops?
0
1 year ago
#2
Frictional force is not dependent on the speed of the object.
The force is proportional to the contact force between the object and surface, and the friction coefficient (a measure of roughness between the two).
When moving, the friction force is always equal to the product of the two. When not moving, the friction is always less than the product of the two.
F=mR (moving)
F<mR (not moving)
The friction coefficient is a constant unique to the two things in contact.
1
1 year ago
#3
(Original post by NaBrO)
Does friction increase closer to a particle stopping?
E.g. if a particle has driving force 10N and friction 5N, when it stops, will friction be 15N (5 + 10)? Or, is the friction force related to the speed at which it stops?
If the frictional force is 5N and the driving force 10N then the object does not stop. It has a resultant force of 10-5 N so it keeps going.

There is also what is called 'static' friction and 'dynamic' friction.
Between 2 objects, the static friction, when there is no movement, is slightly greater than the dynamic friction when they are sliding over each other.
This might be what you are thinking of.
0
1 year ago
#4
(Original post by Stonebridge)
If the frictional force is 5N and the driving force 10N then the object does not stop. It has a resultant force of 10-5 N so it keeps going.

There is also what is called 'static' friction and 'dynamic' friction.
Between 2 objects, the static friction, when there is no movement, is slightly greater than the dynamic friction when they are sliding over each other.
This might be what you are thinking of.
Other way round 0
1 year ago
#5
(Original post by JGLM)
Other way round I assume you mean the OP as got it the wrong way round. In the case when the friction is 10N and driving force 5N, the object does indeed stop.
At that point the object remains at rest with the driving force still 5N and being opposed by a frictional force of 5N.
Zero resultant. No further motion.
The frictional force cannot be greater that the applied force.
Last edited by Stonebridge; 1 year ago
0
1 year ago
#6
(Original post by Stonebridge)
I assume you mean the OP as got it the wrong way round. In the case when the friction is 10N and driving force 5N, the object does indeed stop.
At that point the object remains at rest with the driving force still 5N and being opposed by a frictional force of 5N.
Zero resultant. No further motion.
The frictional force cannot be greater that the applied force.
It can be if it’s moving (and decelerating). I meant that the static friction is always less than (or equal to in limiting equilibrium) the dynamic friction.
0
1 year ago
#7
(Original post by JGLM)
It can be if it’s moving (and decelerating). I meant that the static friction is always less than (or equal to in limiting equilibrium) the dynamic friction.
Indeed. The OP was, though, asking about the case where the object has stopped. Then in that case the frictional force cannot be greater than the applied force, and the applied force needs to be greater than the static frictional force to get it moving again.
I think we've answered the question now. 0
1 year ago
#8
(Original post by Stonebridge)
Indeed. The OP was, though, asking about the case where the object has stopped. Then in that case the frictional force cannot be greater than the applied force, and the applied force needs to be greater than the static frictional force to get it moving again.
I think we've answered the question now. Ahh yes I misinterpreted what you said. Relative to the parallel force, yeah. Lol
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