Coefficient of friction- EK physics 1001 #227

[andrewmalanga]

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A car moving at 20m/s brakes and slides to a stop. If the coefficient of kinetic friction between the pavement and tires is 0.1, how much time is needed for the car to come to a complete stop?

I'm not sure, but I feel like something is missing here (i.e. mass of the car). Anyone care to chime in? I'm about to punt the EK book across the room.

 

[andrewmalanga]

forget about it... i figured it out.

i have to set Uk mg cos(theta) to m x a and solve for a. a=1
then plug a into v=Vi + at
t=20