# Mesuring coefficient of static friction

1. Dec 5, 2007

### kash123

hi,
i am taking this physics course through correspondance and don't have anyone to help me. i am supposed to do a lab on measuring coefficients of friction. purpose of the lab is to determine whether tread design affects the coefficient of static friction for running shoes. i am supposed to use a wooden board, a meter stick and some shoes. i need to write a procedure myself..so here is what i have done so far... i took 4 pieces of shoes noted their make and type, then i measured the horizontal length of wooden board, also assumed mass of shoes...then i placed a shoe on the wooden board and lifted it unlti the shoe began sliding and then i noted the verticl length as well...
now i had to write a hypothesis and a prediction before i started anything. so, i say in my hypothesis that yes tread design as well as shoe design affects the coefficeint of static friction. both are made in a way to have maximum coefficient of static friction inorder for a person or object to have firm grip and don't just slip...
i need help with this, i am sure i could say more than that....thanks in advance everbody.

2. Dec 5, 2007

### stewartcs

The coefficient of static friction is dependent upon the properties of the two materials in contact only.

3. Dec 5, 2007

### kash123

well, i am supposed to use wooden board and a shoe...i'll show you what i haev done so far... the horizontal length of the board is 0.75m... when i place a shoe on top of it and lift it slowly until the shoe begins to slide then wooden board length at that point is 0.52m....so basically, if i need to find the coeeficient of static friction b/w board and shoe..i just divide 0.52/0.75...it gives me coefficient of static friction....now for the Analysis it ask me to discuss my observations by referring directly to the coefficeint of static or kinetic friction that you calculated from the data collected....include in your discussion a report on ways to improve the quality of the data, and any areas of experimental error encountered....
my data is, for four shoes...horizontal length is 0.75m...vertical changes...shoes 1=0.58, 2=0.44,3=0.56,4=0.48...so i get the coefficient of friction like i shown you up there.....just little confuse about the analysisi

Last edited: Dec 5, 2007
4. Dec 5, 2007

### stewartcs

You could use more than one type of shoe, with a different tread pattern, but with the same type of sole (rubber or some other type of material). Then you can determine the coefficient of static friction for each shoe and compare them to each other. They should all be about the same assuming the other properties I listed are about the same. Then you can draw conclusions about the relationship between the coefficient of static friction and the tread pattern.

Last edited: Dec 5, 2007
5. Dec 5, 2007

### kash123

i am supposed to use just the running shoes... and i did use more than one running shoe with different tread patteren... and the coefficient of static friction that i get for all the shoes are 0.69,0.6,0.64,0.72... and for the weight i assume they have almost the same weight... i assume the shoe with the hightest coefficient of static friction provides a better grip...could you be able to tell me more from here ...thanks

6. Dec 5, 2007

### stewartcs

They all look pretty close, so assuming the shoes are the same material, one would conclude that the tread pattern is irrelevant. The slight variations are probably due to the non-exact method of measurement, or possibly some slight material differences.

The point is that the coefficient of static friction depends on just the materials in contact and not the weight, area in contact, tread pattern, etc...

Last edited: Dec 5, 2007
7. Dec 5, 2007

### shawshank

The coefficient of maximum static friction is equal to tan (x) of the triangle before it slips.
Mu = tan(x)
Mu = vertical height / horizontal distance.

The one with a higher coefficient has a rougher surface when it comes in contact with a wooden surface (for basketball players for example). The idea is to keep the coefficient of friction at a reasonable level so the player doesn't slip but also you don't want the friction to be too high, they might twist their ankles. Make sure you look at exactly what comes in contact with the ground and how they deform when pressed against the ground.

8. May 7, 2008

### kkumar

hello kash i am doing the same Physics course

hello kash 123 i am doing the same course and having problem with the lab report too. please let me know if u can help me plz. How far are u in this course . i have just started and have to finished the course yet. you can be of good help to me . Please reply me as soon as possible. Let me know ur email id so that i can mail you in person to discuss a bit abt this course.

thanks

Kumar

9. Jun 17, 2010

### Hop1pop

Im doing the same lab and I am beginning to think the point of this whole assignment is to understand and practice writing labs. :uhh:

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