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keltix
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Do kinetic frictional forces always slow objects?
Generally, yes, but not always. Imagine a box on the floor of a railroad flatcar which is accelerating faster than static friction can support. In that case, kinetic friction between the floor and the box will accelerate the box (until it slides off or bangs into a wall).keltix said:Do kinetic frictional forces always slow objects?
Kinetic frictional force is the force that opposes motion between two surfaces that are in contact and moving relative to each other. It is caused by the roughness of the surfaces and the interlocking of their microscopic bumps and valleys.
Kinetic frictional force acts on objects that are already in motion, while static frictional force acts on objects that are at rest. Additionally, kinetic frictional force is typically weaker than static frictional force.
The magnitude of kinetic frictional force depends on the roughness of the surfaces, the force pressing the surfaces together, and the speed at which the surfaces are moving relative to each other. It also depends on the type of material the surfaces are made of.
The formula for calculating kinetic frictional force is Fk = μkN, where Fk is the kinetic frictional force, μk is the coefficient of kinetic friction, and N is the normal force between the two surfaces.
Kinetic frictional force can be reduced by using lubricants between the two surfaces, making the surfaces smoother, or reducing the force pressing the surfaces together. Additionally, reducing the speed at which the surfaces are moving can also decrease the magnitude of kinetic frictional force.