Coefficient of friction for a shoe sole

[chrispat]

Homework Statement

A person of mass 60kg standing on a horizontal floor attempts to push a large wheeled crate of mass 800kg, which can roll on the same horizontal floor with coefficient of rolling friction equal to ur=0.03. What is the minimum coefficient of friction required between the soles of the person's shoes and the horizontal floor if the person is to succeed in keeping the crate rolling at a constant speed without slipping herself?

I don't understand what force is moving the person forward but I have attempted a solution

Homework Equations

For the crate:

Ff<---crate--------->Fpush

Fnet=Fpush-Ff=0

For the shoe shoes:

Ff<---ss---------->Fpush

Fnet=Fpush-Ff=0

The Attempt at a Solution

For the crate:

Ff=(ur)(m)(g)
=(0.03)(800kg)(9.81m/s^2)=235N

For the shoe soles:

Fnet=(235N)-(us)(60kg)(9.81m/s^2)
us=235/(60)(9.81)=0.399

 

[LowlyPion]

Homework Statement

A person of mass 60kg standing on a horizontal floor attempts to push a large wheeled crate of mass 800kg, which can roll on the same horizontal floor with coefficient of rolling friction equal to ur=0.03. What is the minimum coefficient of friction required between the soles of the person's shoes and the horizontal floor if the person is to succeed in keeping the crate rolling at a constant speed without slipping herself?

I don't understand what force is moving the person forward but I have attempted a solution

Homework Equations

For the crate:

Ff<---crate--------->Fpush

Fnet=Fpush-Ff=0

For the shoe shoes:

Ff<---ss---------->Fpush

Fnet=Fpush-Ff=0

The Attempt at a Solution

For the crate:
Ff=(ur)(m)(g)
=(0.03)(800kg)(9.81m/s^2)=235N

For the shoe soles:
Fnet=(235N)-(us)(60kg)(9.81m/s^2)
us=235/(60)(9.81)=0.399

Welcome to PF.

Looks to me like you understood what needed to happen.
Your method looks good. I won't check the math.

 

[thomate1]

The minimum coefficient of friction required between the soles of the person's shoes and the horizontal floor is 0.399. This means that the friction force between the shoes and the floor must be at least 0.399 times the weight of the person in order for them to successfully keep the crate rolling at a constant speed without slipping themselves. If the coefficient of friction is lower than this, the person will not have enough friction to push the crate forward and will likely slip themselves.