- 1 十年前最愛解答
By Cold-Welding Theory:
When two bodies are in contact, its real area in contact, A', is much less than its apparent area, A. Pressures at the points of contact are extremely high and cause the humps to flatten out until the increased area of contact enables the upper solid to be supported. It is thought that at the points of contact, small, cold welded joints are formed by adhesive forces between molecules which are very close together. These bonds have to be broken and accounts for the frictional force, f, whenthere is relative motion.
- 1 十年前
When an object moves over a surface, there is usually a force opposing its motion.
This force is called friction. In gerenal, friction slows down moving objects.
Friction acts onthe contacting surfaces of two objects when they move over each other. Friction always opposes the motion of an object.