Answer the following question given this paragraph: 

Sliding friction is friction that acts on objects when they are sliding over a surface. Sliding friction is weaker than static friction. That’s why it’s easier to slide a piece of furniture over the floor after you start it moving than it is to get it moving in the first place. Sliding friction can be useful. For example, you use sliding friction when you write with a pencil. The pencil “lead” slides easily over the paper, but there’s just enough friction between the pencil and paper to leave a mark.


Q: What type of friction is friction that acts on objects when they are sliding over a surface?

 Choices:

- spreading friction

- static friction

- rolling friction

- sliding friction

A:
sliding friction
