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## Homework Statement

If the coefficient of kinetic friction between tires and dry pavement is mu_k, what is the shortest distance in which an automobile can be stopped by locking the brakes when traveling at v?

On wet pavement the coefficient of kinetic friction may be only mu_wet. How fast should you drive on wet pavement in order to be able to stop in the same distance as in part (a)? (Note: Locking the brakes is not the safest way to stop.)

## Homework Equations

F = ma

## The Attempt at a Solution

I solved the first part and I got the answer as v^2/(2*ukg). Now I'm stuck on the second part. I attempted all equations but I can't seem to find v because it cancels out on all the equations I tried.

First attempt: third eqn, vf^2 = v^2 + 2adeltax

delta x = v^2/(2*ukg)

a = 2*uwet*g

vf = 0

Also attempted to plug in first eqn of motion to find the time, and then plug in the second eqn of motion to find v but in the end, it still cancels out. Pls tell me what I did wrong....