How to find coefficient of friction *Without* mass?

[APphysicsSenior]

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!

 

[ehild]

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?

 

[APphysicsSenior]

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!

 

[ehild]

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.