# Kinetic friction ratio problem

"A driver makes and emergency stop and locks up the brakes of the car, which skids to a stop on dry concrete. Consider the effect of rain on this scenario. If the coefficients of kinetic friction for rubber on dry and wet concrete are μk (dry)=0.80 and μk(wet)=0.50, how much farther would the car skid (expressed in percentage of the dry-weather skid) if the concrete were instead wet?"

I thought it might just be dividing dry/wet coefficients and multiplying by 100 to get the percentage. I don't think this is right, as the professor was implying there was more to solving it than that. He talked about (dry-wet)/dry to work out the answer, but it wasn't just the μ values. I feel like I missed something that should be obvious. Any help will be greatly appreciated!

NascentOxygen
Staff Emeritus

Wild guessing is never the recommended approach.http://physicsforums.bernhardtmediall.netdna-cdn.com/images/icons/icon13.gif [Broken] Do you have some equations to throw around and see what you can connect up?

So far, we seem to have force and distance, so you need equations to allow you to relate those.

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cepheid
Staff Emeritus