Physics Problem: Work and Force on a Skier Coasting Uphill with Friction

AI Thread Summary
The discussion revolves around a physics problem involving a skier coasting uphill with friction. The skier's mass is 71.8 kg, and they start with an initial speed of 8.84 m/s, coasting up a 25.1° slope for 2.10 m, ultimately reaching a speed of 3.41 m/s. The work done by the kinetic frictional force is calculated to be -1761 J. Participants seek clarification on how to determine the magnitude of the kinetic frictional force, with references to the definitions of work done and energy conservation. The conversation emphasizes the relationship between kinetic energy, potential energy, and the work-energy principle.
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A 71.8-kg skier coasts up a snow-covered hill that makes an angle of 25.1 ° with the horizontal. The initial speed of the skier is 8.84 m/s. After coasting a distance of 2.10 m up the slope, the speed of the skier is 3.41 m/s. (a) Find the work done by the kinetic frictional force that acts on the skis. (b) What is the magnitude of the kinetic frictional force?

Part a= -1761 J

I Just can't figure out how to find part b
 
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What is the definition of work done?
 
Work done is equal to KE+PE so kinetic energy final + mgh- kinetic energy intial+ mgh where kinetic energy is 1/2mvsquared
 
There is another definition of work done which says
W=r \cdot F

Try it now.
 

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