What is Kinetic friction: Definition and 509 Discussions

Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. There are several types of friction:

Dry friction is a force that opposes the relative lateral motion of two solid surfaces in contact. Dry friction is subdivided into static friction ("stiction") between non-moving surfaces, and kinetic friction between moving surfaces. With the exception of atomic or molecular friction, dry friction generally arises from the interaction of surface features, known as asperities (see Figure 1).
Fluid friction describes the friction between layers of a viscous fluid that are moving relative to each other.Lubricated friction is a case of fluid friction where a lubricant fluid separates two solid surfaces.Skin friction is a component of drag, the force resisting the motion of a fluid across the surface of a body.
Internal friction is the force resisting motion between the elements making up a solid material while it undergoes deformation.When surfaces in contact move relative to each other, the friction between the two surfaces converts kinetic energy into thermal energy (that is, it converts work to heat). This property can have dramatic consequences, as illustrated by the use of friction created by rubbing pieces of wood together to start a fire. Kinetic energy is converted to thermal energy whenever motion with friction occurs, for example when a viscous fluid is stirred. Another important consequence of many types of friction can be wear, which may lead to performance degradation or damage to components. Friction is a component of the science of tribology.
Friction is desirable and important in supplying traction to facilitate motion on land. Most land vehicles rely on friction for acceleration, deceleration and changing direction. Sudden reductions in traction can cause loss of control and accidents.
Friction is not itself a fundamental force. Dry friction arises from a combination of inter-surface adhesion, surface roughness, surface deformation, and surface contamination. The complexity of these interactions makes the calculation of friction from first principles impractical and necessitates the use of empirical methods for analysis and the development of theory.
Friction is a non-conservative force – work done against friction is path dependent. In the presence of friction, some kinetic energy is always transformed to thermal energy, so mechanical energy is not conserved.

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  1. mazia

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    So, ignore the -0.72, I was just trying to see if I had a sign error (I then remembered magnitude is absolute value) but basically: Since the weight is 12.0N, theta is 53.1, and the coefficient of kinetic friction is 0.100, I just plugged those values into the equations above...
  2. Argonaut

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  3. K

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  4. Arwing

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  5. J

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  6. DonutHole

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    Fn = 53 X 9.81 X cos 22 Fnet = 524 – 53 X 9.81 sin 22 + μ X 53 X 9.81 cos 22
  7. P

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  8. guyvsdcsniper

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  9. jamiebean

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  10. Leo Liu

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  11. Thijske

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  12. Like Tony Stark

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  13. Addez123

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  14. P

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  15. Specter

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  16. J

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  17. A

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  18. navneet9431

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  19. S

    Kinetic friction direction on two stacked blocks

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  20. JessiLim

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  21. Ushitha Dissanayake

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  22. physicsquestionboi

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    A steel washer is suspended inside an empty crate from a light string attached to the top of the crate. The crate slides down a long ramp that is inclined at an angle of 37 above the horizontal. The crate has mass 154 kg. You are sitting inside the crate; your mass is 61 kg. As the crate is...
  23. F

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  24. Z

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  25. B

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  26. F

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    Homework Statement Homework Equations W = Fk d cos θ Fk = FN μκ The Attempt at a Solution Here's my work : m = 1 kg vi = 10 m/s vf = 0 m/s xi = 0 m xf = 0.1 m d = 0.1 m k=60 N/m μκ=? The work done be the frictional force : W = Fκ d cos θ = FN*μκ*d*cosθ = mg μκ d cos 180 =...
  27. F

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  28. parshyaa

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  29. J

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  30. APphysicsSenior

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  31. A

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  32. A

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  33. M

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  34. B

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  35. K

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  36. T

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    Homework Statement A 5.72 kg block is released from rest on an inclined surface. The incline makes an angle of 25.0 degrees relative to horizontal. The block is known to be traveling at a speed of 1.33 m/s after sliding a distance of 2.60 m along the incline. How much work was done on the block...
  37. H

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  38. S

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  39. K Wils

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  40. P

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  41. N

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  42. Her0

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  43. R

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  44. K

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  45. S

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  46. R

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    Homework Statement A child slides down a slide with a 28 degree incline , and at the bottom her speed is precisly half what it would have been if the slide had been frictionless. Calculate the coefficient of kinetic friction between the slide and the child. Homework Equations Newtons second...
  47. audrey1203

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