Forces and friction

  • #1
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Homework Statement


A student measures the the force required topull a box along the floor and then the force required to lift the box onto a table. Which is greater?



Homework Equations




The Attempt at a Solution


[/B]
Is it the force to lift the box since frictional force is the normal force or weight times the coefficient of friction which is between 0 and 1?
 

Answers and Replies

  • #2
SammyS
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Homework Statement


A student measures the the force required topull a box along the floor and then the force required to lift the box onto a table. Which is greater?



Homework Equations




The Attempt at a Solution


[/B]
Is it the force to lift the box since frictional force is the normal force or weight times the coefficient of friction which is between 0 and 1?
The coefficient of friction can be greater than 1.
 
  • #3
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The coefficient of friction can be greater than 1.
Is there a reference saying that the coefficient of kinetic friction can be greater than 1?

Chet
 
  • #4
SammyS
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Is there a reference saying that the coefficient of kinetic friction can be greater than 1?

Chet
It is highly unusual even for static friction.

I have seen a few values listed with μk > 1 .

Al on Al showed 1.3 & 1.4 in a couple of tables.

Lead on steel in one or two tables -- I don't recall the value.

I don't why intrinsically that it's not possible for μk > 1 , but I don't have any good references.
 
  • #5
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4,725
It is highly unusual even for static friction.

I have seen a few values listed with μk > 1 .

Al on Al showed 1.3 & 1.4 in a couple of tables.

Lead on steel in one or two tables -- I don't recall the value.

I don't why intrinsically that it's not possible for μk > 1 , but I don't have any good references.
Thanks. Very interesting. I'll file this away in my brain.

Chet
 

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