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
Moisture on your fingers only gives you better grip if they’re too dry in the first place. By adding moisture you make them softer which makes them stick better to paper and plastic bags.
But adding moisture in between your fingers actually makes them more slippery as well, especially if you’re rubbing your hands together your hands stick together better if they’re dry than if you dip them in water before doing so. This is because the water forms a layer on top of your skin which prevents direct contact with the skin on the other hand, as there will usually be a thin film made up of water in between the hands.
And this thin film of water is also the problem when it comes to tarmac, because what happens when tarmac is wet is that because the vehicle is moving so fast the water actually prevents direct contact between the tarmac and the tires to some degree. Especially if you start sliding as this pushes water in front of the tires which eventually forms a tiny wave that goes in between the tires and the tarmac.
**Anyhow, that’s a short explanation of some of what’s going on but it’s very far from being a comprehensive or perfect explanation, hopefully someone else will make a better one.**
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