If you try to gently push the book across the table with the tip of your ... forces is seen in earthquakes and landslides.

"The most intriguing thing about friction is that it is proportional ... operate at many different scales -- ranging from books sliding across tables to massive scales such as Earth's tectonic ...

Imagine sliding a book across a desk. There's friction at all points where the ... Suddenly that book is practically racing across the table if you so much as nudge it. Ball bearings take this ...

Friction is a force between two surfaces that are sliding, or trying to slide, across each other. For example, when you try to push a book along the floor, friction makes this difficult.