# AP Physics

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At an accident scene on a level road, investigators measure a car's skid mark to be 98 m long. It was a rainy day and the coefficient of friction was estimated to be 0.38. Use these data to determine the speed of the car when the driver slammed on (and locked) the brakes.

• AP Physics -

Well, friction force is mg*mu

That has to equal m*a
a=g*mu

Vf^2=0=Vi^2-2*a*d
solve for Vi

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