When I need to turn a page, water adds a bit more friction making it easier to turn the page. Yet when driving, water reduces friction between wheels and the road.
Why can it do both?
In: 3
In the case of the car, the water acts as a lubricant – it gets in between the tire and the road surface and allows them to move over each other more freely by preventing them from getting close enough together that the rough surfaces of the road and tire rub against each other. In the case of turning a page, the water sticks to your skin and the fibres of the paper by adhesion – the water molecules are very slightly attracted to the paper and to your skin, and then cohesion, the force between the water molecules themselves, holds the water together so that when you move your finger, you pull on the water, and the water pulls on the paper, and so the paper sticks to your finger.
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