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**1. Homework Statement**

A car is traveling at 50 mi / hr on a horizontal highway

a. If the coefficient of static friction between the road and tires on a rainy day is 0.100, what is the minimum distance in which the car will stop?

b. What is the stopping distance when the surface is dry and μ

_{s}= 0.600?

**2. Homework Equations**

∑ f = ma

f

_{s}= (μ

_{s})(normal force)

Xf = Xi + (Vi)(t) + (1/2)at

^{2}

**3. The Attempt at a Solution**

Do not know where to start, please help.

Part a:

∑ Fx = ma - f

_{s}= 0

f

_{s}= (μ

_{s})(normal force)

∑ Fy = (normal force) = mg

ma = f

_{s}therefore ma = (μ

_{s})(normal force)

a = (μ

_{s})(normal force) / mass

Now: vf = 0

vi = 73.3 ft / second

Xf = Xi + Vi t + (1/2)at

^{2}

0 = 50 mi / hr + [ (0.100)(normal force) / mass ][t

^{2}]