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Friction

Friction originates from forces between atoms and molecules when surfaces are in contact. For example, friction occurs when a body moves on a rough surface or through a fluid medium (water, air, etc.). There are two types of friction:
1.
The Static force of friction ( fs ) is the force of friction between two objects when there is no motion.
2.
The Kinetic force of friction ( fk ) is the force of friction between two objects when there is motion.
Consider a block on a rough surface. Apply an external force Fext to the block.

 

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10/9/1997