How to find coefficient of friction *Without* mass?

In summary: You can then solve for μ by dividing both sides by mg and plugging in the values you know. Remember to convert the speed from km/h to m/s before using it in the equation.In summary, a car traveling at 97 km/h can stop in 48 m on a level road. To determine the acceleration of the car, you can use the equation Vf^2=Vo^2 +2aΔx and calculate the acceleration to be -7.53 m/s^2. To determine the coefficient of friction between the tires and the road, you can use the equation Ff=μmg and set it equal to Ff=ma. By canceling out the mass and solving for μ, you can
  • #1
APphysicsSenior
4
0
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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  • #2
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?
 
  • #3
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!
 
  • #4
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.
 

1. What is the coefficient of friction?

The coefficient of friction is a measure of how much resistance there is between two surfaces in contact when one surface moves across the other. It is a dimensionless number, typically denoted by the Greek letter mu (µ).

2. Why is it important to find the coefficient of friction without mass?

Finding the coefficient of friction without mass allows for a more accurate comparison between different materials and surfaces. It eliminates the potential confounding factor of mass, which can vary and affect the frictional force between surfaces.

3. How do you calculate the coefficient of friction without mass?

The coefficient of friction can be calculated by dividing the force required to move an object over a surface by the normal force (perpendicular force) between the two surfaces. This calculation can be done without including the mass of the object.

4. What are some common methods for finding the coefficient of friction without mass?

Some common methods include using an inclined plane, a friction block, or a force sensor. These methods involve manipulating the angle or force required to move an object over a surface and using this information to calculate the coefficient of friction.

5. Can the coefficient of friction be different for different materials even without mass?

Yes, the coefficient of friction can vary for different materials even when mass is not a factor. This is because the coefficient of friction is influenced by factors such as surface roughness, type of material, and presence of lubricants.

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