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

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SUMMARY

The discussion focuses on calculating the stopping distance of a 900kg car traveling at 80km/h when brakes are applied, with a coefficient of kinetic friction of 0.45. The relevant equations include Newton's second law (F=ma) and kinematic equations (D=vt, Vf=Vi+at). The primary challenge identified is determining the force of friction, which is essential for calculating the deceleration and subsequently the stopping distance. Participants emphasize the importance of understanding the relationship between friction, acceleration, and distance in solving this problem.

PREREQUISITES
  • Understanding of Newton's second law (F=ma)
  • Knowledge of kinematic equations (D=vt, Vf=Vi+at)
  • Familiarity with the concept of kinetic friction and its coefficient
  • Basic algebra for solving equations
NEXT STEPS
  • Learn how to calculate the force of friction using the coefficient of friction
  • Study the derivation of stopping distance formulas in physics
  • Explore real-world applications of kinematic equations in automotive safety
  • Investigate the effects of varying coefficients of friction on stopping distances
USEFUL FOR

Students studying physics, automotive engineers, and anyone interested in understanding vehicle dynamics and safety calculations.

whatabootme
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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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