# Coefficient of friction HELP please!

1. Jan 1, 2012

### allelil13

1. The problem statement, all variables and given/known data

We have an investigative project and our group's topic is inclined plane surfaces. I need help in getting the coefficient of friction of the toy car. We will investigate the coefficient of friction of different surfaces. Our teacher didn't (and will never) discuss to us this topic. PLEASE HELP!!!

Speed of the toy car = 3s

2. Relevant equations

3. The attempt at a solution

2. Jan 1, 2012

### JHamm

You're going to have to show us that you've given it a go before we help, what do you know about this? Do you have any ideas?

3. Jan 1, 2012

### allelil13

We're actually working already on the Chapter 4 which we need to submit on Wednesday. We just need to compute for the coefficient of friction then we are done.

4. Jan 1, 2012

### JHamm

Do you have any idea how you'd compute it?

5. Jan 1, 2012

### allelil13

No. Not really.. I looked for formulas over the net but it made me more confused.

Last edited: Jan 1, 2012
6. Jan 1, 2012

### JHamm

Since you have a distance and a time I'd go for a kinematics equation, for that you'll need to find an expression for the net acceleration of the car along the ramp

7. Jan 1, 2012

### allelil13

How will I get that?
I didn't expect coefficient of friction to be this complicated. Gahh..

8. Jan 1, 2012

### JHamm

To find acceleration use newton's second law, what forces act on the car?

9. Jan 1, 2012

### allelil13

a = F/m? Idk, gravity? :rofl:

10. Jan 1, 2012

### allelil13

1. The problem statement, all variables and given/known data

We have an investigative project and our group's topic is inclined plane surfaces. I need help in getting the coefficient of friction of the toy car. We will investigate the coefficient of friction of different surfaces. Our teacher didn't (and will never) discuss to us this topic. PLEASE HELP!!!

Speed of the toy car = 3s

2. Relevant equations

3. The attempt at a solution

11. Jan 1, 2012

### Alaa Mahmoud

I don't understand it well >>but there is normal force,F gravity and Friction force

12. Jan 1, 2012

### allelil13

How will I get those?

13. Jan 2, 2012

### JHamm

Well the frictional force is what you're trying to find so it will just have to be assigned some character $F_{friction}$, now the other force you want to consider is gravity, can you get the component of gravity along the ramp?

14. Jan 2, 2012

### Alaa Mahmoud

friction force is always to the opposite of motion
we have two component of gravity : gmsinx ... gmcosx
&the normal force :normal to the surface
Then we can use Newton's laws to estimate F(friction)

15. Jan 2, 2012

### cupid.callin

Hi allelil13

Do you know about the relation Ffriction = μN ??

Can you draw all the forces acting on the toy car when placed on a ramp?

16. Jan 2, 2012

### bm0p700f

A good text book should help here.

However if you don't have one you will need to draw a force diagram and write an equation weight of the car down the slope. In a static case where the car is not sliding or rolling the weight down the slope will equal the friction force up the slope. You should be able to rearrnage and find what you need.