Problem 30 (Similarity). The coefficient of kinetic friction between a car's tires and the if the pavement is dry; lw if the pavement is wet. If the car is going

at pavement is speed va on dry pavement, it can stop in a distance x. If the pavement is wet, it must goat a speed of vw in order to stop in the same distance. What is the relationship between v_{w} \text { and } v_{d} ? \text { (a) } v_{w v}=\sqrt{\frac{\mu_{w v}}{\mu_{d}}} v_{d} \text { (b) } v_{w}=\frac{\mu_{w} v}{\mu_{d}} v_{d} \text { (c) } v_{w}=\frac{\mu_{d}^{2}}{\mu_{w}^{2}} v_{d} \text { (d) } v_{w v}=\frac{\mu_{d}}{\mu_{w v}} v_{d} \text { (e) None of these }

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