How Do You Calculate the Stopping Distance of a Car Using Kinetic Friction?

AI Thread Summary
To calculate the stopping distance of a car, the force of friction must be determined using the coefficient of kinetic friction, which is 0.45 in this case. The stopping force can be calculated as the product of the coefficient of friction and the normal force, which equals the weight of the car. Using Newton's second law (F=ma), the acceleration can be found, and subsequently, the stopping distance can be calculated using kinematic equations. The initial velocity of the car is 80 km/h, which needs to be converted to meters per second for accurate calculations. Understanding these relationships is essential for solving the problem effectively.
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Homework Statement


A 900kg car is moving on a level road at 80km/h. If the brakes are applied, what is the distance it will take to stop if the coefficient of kinetic friction between the tires and the road is 0.45.


Homework Equations


F=ma
D=vt
Vf=Vi+at
...
Really basic Kinematics and Forces(grade 11 level)


The Attempt at a Solution


I need help finding the formula for the Force applied. I find it really hard because I am not sure if the velocity is constant or not. I don't really know how to explain my attempt to solve it. I tried using D=vt but I can't find time without acceleration; without acceleration I am not able to find distance, etc.

How would you solve this kind of problem? I tried to google for the formula but I can't seem to find any that will be suitable for this problem.

Help would be very much appreciated.
 
Physics news on Phys.org
Hello, Whatabootme. Welcome to PF.

The force that's stopping the car is the force of friction. Do you know how to calculate the force of friction using the value of the coefficient of friction?
 

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