Question

Define sliding friction

Answer 1

Sliding friction is also known as kinetic friction, or moving friction, and is defined as the force that is required to keep a surface sliding along another surface. Hans learns a couple of things about sliding friction that may help him with his robot battles:
Sliding friction depends only on two variables: the materials in question and the weight of the object. Changing the surface area in contact does not change the sliding friction.
Sliding friction for most materials is less than the static friction. Exceptions include metals, which have static and sliding friction coefficients that are essentially the same, and very small surfaces, where molecular attraction forces take over.