# Find the coefficient of friction between the car tires and the road.

#### BlackCatXIII

help needed!!!! ><

Someone plz help me with this question!!!
(at least show me how to do it~!)

A car slams on its brakes and skids to a halt from 65km/h in 2.67s. Find the coefficient of friction between the car tires and the road.

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#### HallsofIvy

Homework Helper
You know the change in speed in a given time (65km/h in 2.67s) so you can find the acceleration. IF you knew the mass of the car, then you could calculate the friction force from F= ma.
Since you are asked for the "coefficient of friction" rather than the friction force itself, you don't need the mass: The friction force is F= k*weight= kmg.

That is, F= ma= kmg so k= a/g- the mass cancels out.

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