What is the kinetic friction coefficient?

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SUMMARY

The discussion centers on calculating the kinetic friction coefficient for a skier sliding down a 20-degree slope at constant speed. Key equations include F = μN and F = ma, with the realization that acceleration is zero due to constant speed. Participants emphasized the importance of drawing a free body diagram (FBD) to visualize forces acting on the skier, particularly the frictional force and gravitational components along the slope. The correct approach involves recognizing that the force of friction must balance the component of gravitational force acting down the slope.

PREREQUISITES
  • Understanding of Newton's laws of motion
  • Familiarity with free body diagrams (FBD)
  • Knowledge of the relationship between friction and normal force
  • Basic trigonometry for resolving forces on an incline
NEXT STEPS
  • Study the derivation of the kinetic friction coefficient using F = μN
  • Learn how to construct and analyze free body diagrams (FBD) for inclined planes
  • Explore the effects of angle on frictional forces in physics
  • Review the concept of static vs. kinetic friction and their applications
USEFUL FOR

Students in physics courses, educators teaching mechanics, and anyone interested in understanding the dynamics of motion on inclined surfaces.

Kailee
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Homework Statement


A skier is sliding down a 20o slope at constant speed, what is the kinetic friction coefficient?

Homework Equations


E = 1/2 mv2
W = Fd
F = ma
F = μN = μmg

The Attempt at a Solution


Attempted to use ma = μmgsin20, which crosses out the masses since mass was not given, but the skier is going at a constant speed so I'm assuming acceleration would be zero. Though I'm not sure how to continue the question or if I'm on the right track. Thanks in advance!
 
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Have you tried drawing a force diagram? If not, start here. You'll notice that your expression for the force of friction is incorrect (the μmg part), and that you have left out a force along the slope (the component of a force to be more specific)

You are correct that the acceleration would be zero.
 
Ah, figured out what I was doing wrong, thank you! :)
 
You're right, the acceleration is zero. But you are missing one force. Why don't draw an FBD of the skier on the incline.
 

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