Why does water affect friction differently in different situations?

[ntd252]

Hello everyone!
I am Duong (Dương), I am from Vietnam, 16 years old. So my English grammar isnot good, i am sorry!
I have some problems about friction, I can't understand.
First, when the road is slippery after the rain, the car or orther verhicles (in the road) are very difficult to drive. This means "water reduces friction between the hire with the road."
Second, when the road is flooded, the car is difficult to drive, too. this means "water increases friction"
Beside, we use small water in the finger to turn the page of the book, it means that water increases friction, too
So, it is ridiculous, not only reducing friction, but also increase friction, so why?i need explaining
Thank you very much! Have a nice day!

 

[A.T.]

So, it is ridiculous, not only reducing friction, but also increase friction, so why?

Without any water you will die of thirst, but with too much water you will drown. Is this also a ridiculous paradox to you, that you cannot understand?

The road is slippery after the rain, because the wheels glide on a water film. On a flooded road the water has to be moved out of the way, so it creates drag. The book page sticks to the wet finger due to adhesive forces.

 

[ntd252]

I know. Read again my post. The book page sticks to the wet finger, because of friction is increased. I want to understand that, why can water reduce friction and increase friction?how does water affect surface between road and car's tire?

 

[A.T.]

The book page sticks to the wet finger, because of friction is increased. I want to understand that,

http://en.wikipedia.org/wiki/Adhesion

how does water affect surface between road and car's fire?

http://en.wikipedia.org/wiki/Lubricant
http://en.wikipedia.org/wiki/Aquaplaning
http://en.wikipedia.org/wiki/Drag_(physics)