# Forces and friction

## 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?

## The Attempt at a Solution

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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
Staff Emeritus
Homework Helper
Gold Member

## 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?

## 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
Mentor
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
Staff Emeritus
Homework Helper
Gold Member
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.

Chestermiller
Mentor
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