Why moistening your fingers helps increase their traction with respect to opening thin plastic bags or flipping through paper, but moisture on a road decreases the traction of your car tires?
In: 5
Your fingers and the paper can absorb some of the moisture, which prevents a layer of water from forming between the two surfaces. Tire rubber and road pavement are non-absorptive to water, so the water will form a lubricating layer between the rubber and the road. This is why tire treads have voids to let water flow out from between the two surfaces.
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