Kinetic Friction
This page defines and describes kinetic friction. Some of the information presented on this page is also present on the Friction page.
The Main Idea
Kinetic friction is a type of Friction between two touching objects that are moving with respect to each other at their point of contact. When two objects touch each other and there is sliding between their surfaces of contact, they exert a kinetic friction force on each other. The kinetic friction force acting on each object acts in a direction opposite to its direction of motion relative to the other object. If the kinetic friction force is the only force acting on each object, they will eventually come to rest relative to each other, at which point the friction force between them becomes static. For example, consider a crate sliding across the floor. It will slow down and eventually come to rest due to the kinetic friction force between it and the floor, unless another force acts on it, such as the pushing of a person that wants to keep the crate moving. Kinetic friction force within a system lowers the system's kinetic energy, converting it to Thermal Energy. In other words, sliding between surfaces causes the surfaces to heat up. Usually in mechanical physics, this thermal energy is no longer considered part of the system and is considered lost because it usually dissipates into the environment without ever being converted back into mechanical energy. This means kinetic friction does negative work on the system. In addition to dissipating energy as thermal energy, kinetic friction may also dissipate a smaller amount of energy as sound, and can wear down surfaces if sufficiently intense.
Understanding work done by kinetic friction
A Mathematical Model
A Computational Model
Examples
1. (Simple)
2. (Middling)
3. (Difficult)
Connectedness
See also
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Further reading
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External links
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