Forces & Friction: Which is Greater?

[lola2000]

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?

 

[SammyS]

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.

 

[Chestermiller]

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

 

[SammyS]

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 μ_k > 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 μ_k > 1 , but I don't have any good references.

 

[Chestermiller]

It is highly unusual even for static friction.

I have seen a few values listed with μ_k > 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 μ_k > 1 , but I don't have any good references.

Thanks. Very interesting. I'll file this away in my brain.

Chet