# How to find Coefficient of Friction w/ Fa and mass?

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1. Mar 23, 2015

### HomiesontheRise

1. The problem statement, all variables and given/known data
A team of six poodles are pulling a 14.0 kg sled at 8.0 m/s

IF the dogs are applying a 66N force, find the coefficient of kinetic friction

2. Relevant equations
Ff=u*Fn
Fnet=ma
Fnet=(-Ff)+Fa

3. The attempt at a solution
I honestly have no clue where to start for this question.

2. Mar 23, 2015

### PhanthomJay

Well you have correctly listed the relevant equations, now first identify what the acceleration is and solve. Read the problem carefully.

3. Mar 23, 2015

### HomiesontheRise

So I started by finding the Net Force which was 0 due to the fact that there is no acceleration (velocity is constant).
Then found Force of Friction using Fnet and Fa with the formula Fnet=Fa+(-Ff).
Then found Fn using Fn=mg.
Finally, I user Ff=Fn*u to find u

MY WORK
1.
Fnet=0 Fnet-Fa=-Ff 0-66=-Ff -66=-Ff
2.
Fn=mg Fn=14kg*9.8 Fn=137.2
3.
Ff=u*Fn u=Ff/Fn 66/137.2=u 0.48=u

4. Mar 23, 2015

### HomiesontheRise

Please tell me if you see any errors in my calculations

5. Mar 23, 2015

### HomiesontheRise

Does this look right?
1.
Fnet=0 Fnet-Fa=-Ff 0-66=-Ff -66=-Ff
2.
Fn=mg Fn=14kg*9.8 Fn=137.2
3.
Ff=u*Fn u=Ff/Fn 66/137.2=u 0.48=u

6. Mar 23, 2015

Look
Looks good!