How to find coefficient of friction *Without* mass?

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To find the coefficient of friction without knowing the mass of the car, first determine the acceleration using the equation Vf^2 = Vo^2 + 2aΔx, which yields -7.53 m/s². The force of friction can be expressed as Ff = ma, and also as Ff = μmg, allowing the mass to cancel out when both equations are set equal. This results in the equation μ = a/g, where g is the acceleration due to gravity. By substituting the calculated acceleration into this equation, the coefficient of friction can be determined. This method effectively allows for the calculation of friction without requiring the mass of the vehicle.
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A car traveling at 97 km/h can stop in 48 m on a level road
a.) Determine the acceleration of the car
b.) Determine the coefficient of friction between the tires and the road

Homework Equations

: Vf^2=Vo^2 +2aΔx
μ=Ff/mg[/B]

3. I have part A, I got -7.53 m/s^2, but I can't seem to figure out how to find the coefficient of friction without the mass of the car. Help on part B would be MUCH appreciated!
 
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APphysicsSenior said:
A car traveling at 97 km/h can stop in 48 m on a level road
a.) Determine the acceleration of the car
b.) Determine the coefficient of friction between the tires and the road

Homework Equations

: Vf^2=Vo^2 +2aΔx
μ=Ff/mg[/B]

3. I have part A, I got -7.53 m/s^2, but I can't seem to figure out how to find the coefficient of friction without the mass of the car. Help on part B would be MUCH appreciated!
Knowing the deceleration, you can write the force of friction as Ffr=ma. How do you write the force of friction in terms of the coefficient of friction, mass and g?
 
So you would say that Ff=ma and Ff=μmg, then set them equal to each other so the mass cancels out? That makes sense, i'll try that. Thanks!
 
APphysicsSenior said:
So you would say that Ff=ma and Ff=μmg, then set them equal to each other so the mass cancels out? That makes sense, i'll try that. Thanks!
Yes, the mass cancels.
 

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