[nicholas french]

nicholas french asked the Naked Scientists:
   
On a podcast a few days ago a woman asked why licking your finger helped you turn a page, and if it is because the water molecules allow the surfaces to get closer to each other, why is it roads are slippery when you drive on them while they are wet?

What do you think?

[Don_1]

Roads tend to be slippery when wet due to oil, worn rubber and other dirt and dust on the surface. There is also the fact that when driving, the wheels of a car are turning, a damp finger on a page is dragged, causing far more friction and dispelling some of the moisture from the finger onto the paper, and the wheels of a car will always have some water between them and the road surface due to aquaplaning. Make your finger too wet when turning the page of a glossy magazine, and your finger will slide until sufficient water has been dispelled.