There are four types of friction: static, sliding, rolling, and fluid friction. The last three are also grouped under the term kinetic friction. The first three occur between solid surfaces; fluid ...

Watch this video to learn more about friction. Find out about different types of friction and how we can increase or reduce it. Friction is a force between two surfaces rubbing against each other.

To me, it represents another example of shifting work to the customer while adding new forms of friction to the shopping experience. Self-checkouts, anyone? Anyone who has tried to buy razors ...