Understanding 2D Motion: Finding Speed on a Slope

AI Thread Summary
A 42.5kg skier descends a hill with a 42-degree slope and a kinetic friction coefficient of 0.180, raising the question of their speed after 4.56 seconds. The discussion involves calculating forces using a free body diagram, where the gravitational force component and normal force are considered. The maximum frictional force is calculated as 76.5N, leading to confusion about whether to apply net force equations or motion equations. The direction of the frictional force is debated, with implications for the skier's movement. Understanding these forces is crucial for determining the skier's speed down the slope.
thewestbrew
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Homework Statement



A 42.5kg person is going down a hill sloped at 42.0 degrees. The coefficient of kinetic friction between the snow and skis is 0.180. How fast is the skier going 4.56 seconds after starting from rest?


Homework Equations



Is ffkmax equal to net force?

The Attempt at a Solution


coefficient of kinetic friction:.180 t=4.56 mass=42.5kh Angle=42 degrees Vo=0

I created a free body diagram.

I used (mg)(cos 42) to get total force going opposite of FN. I made that force equal to FN and plugged the number into the equation ffkmax=coefficient(.180)*FN(315.83).

Got 76.5N=ffkmax. Now I am not sure if i use fnet=ma or a motion equation.
 
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thewestbrew said:
Is ffkmax equal to net force?
Which way does the frictional force point, up or down the slope? If it were the only force in that direction, which way would the skier move?
 

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