Solving Kinetic Friction: Find Coefficient of Friction from Car Stop

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Homework Help Overview

The discussion revolves around a physics problem involving kinetic friction, specifically determining the coefficient of kinetic friction for a car that stops after applying brakes. The scenario includes a car moving at 20 m/s that comes to a stop after traveling 40 m.

Discussion Character

  • Exploratory, Mathematical reasoning

Approaches and Questions Raised

  • The original poster expresses uncertainty about how to incorporate the given data into the relevant equation. Some participants suggest the need for an additional equation to relate the variables. One participant proposes a method to calculate acceleration using the kinematic equation and then relates it to the coefficient of friction.

Discussion Status

The discussion includes attempts to clarify the relationship between the variables involved in the problem. A participant provides a calculation for acceleration and attempts to derive the coefficient of kinetic friction, while the original poster acknowledges the assistance received.

Contextual Notes

There is a mention of needing to balance forces and the relationship between acceleration and gravitational force, but the original poster's initial confusion about incorporating the data remains evident.

mels
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Homework Statement



A car is moving with a speed of 20m/s when the brakes are applied. The wheels lock (stop spinning). After traveling 40m, the car stops. Determine the coefficient of kinetic friction between the tires and the road.

Homework Equations



Fk=uk x Fn

The Attempt at a Solution



I don't know how to encorporate the given into the equation !
 
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There's another equation you need, one that puts all the given data together.
 
You can apply simple formula...

calculate the acceleration 'a'... by
(square of final velocity)-(square of initial velocity)=2x a x distance

a=20x20/(2x40)
a=5

balance the force
uk x mass x g = mass x a
uk=a/g
uk=5/10=0.5
 
Last edited by a moderator:
okay thank you ! i really appreciate it :)
 

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