Solving for Slope Angle from Kinetic Friction

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Homework Help Overview

The problem involves a skier traveling at a constant speed on a ski slope, with the goal of finding the angle of the slope given the kinetic coefficient of friction. The context is rooted in dynamics and frictional forces.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • The original poster attempts to relate the forces acting on the skier, expressing concerns about the absence of weight in their calculations. They question how the constant velocity influences the forces and whether it factors into the equations. Other participants suggest that missing information may cancel out in the equations and emphasize the importance of expressing forces involved.

Discussion Status

Participants are actively engaging with the problem, with some providing hints and guidance on how to approach the force balance. There is a recognition of the need to equate forces due to the constant speed, but no explicit consensus on the solution has been reached.

Contextual Notes

The discussion highlights constraints such as the lack of specific values for weight or mass, which are typically necessary for solving such problems. Participants are navigating the implications of these missing variables in their reasoning.

supraroy19
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A skier is traveling at a constant speed of 4 m/s on a ski slope. The kinetic coefficient of frictionbetween her skis and the slope is 0.2. Find the angle of the slope.

attempt:

sin feda = f/w but i have no weight
f=mgsinfeda and N=mg cos feda
all of this ends up being mu=tan feda but don't understand where the Velocity in the problem factors in or if since its a constant force and the net sum of a constant moving anything is zero if it does not factor into the equation at all. i have drawn a vector sum diagram with net sum =0. We worked out one of these in class but he gave us the wieght of the person and the angle. i can't figure out how to do it without those variables.
 
Last edited:
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I will gladly assist you with the problem, but you must show your attempt at a solution before I can do so as per PF rules.

EDIT: Attempt added noted.
 
Last edited:


supraroy19 said:
A skier is traveling at a constant speed of 4 m/s on a ski slope. The kinetic coefficient of frictionbetween her skis and the slope is 0.2. Find the angle of the slope.

attempt:

sin feda = f/w but i have no weight
f=mgsinfeda and N=mg cos feda
all of this ends up being mu=tan feda but don't understand where the Velocity in the problem factors in or if since its a constant force and the net sum of a constant moving anything is zero if it does not factor into the equation at all. i have drawn a vector sum diagram with net sum =0. We worked out one of these in class but he gave us the wieght of the person and the angle. i can't figure out how to do it without those variables.

Generally you will find with these sorts of problems that information that is not given (such as weight or mass) will eventually cancel out in the equations involved. So unless you're "addicted" to plugging in numbers as soon as possible for every case, there shouldn't be a problem.

In this case the skier is said to be traveling at a constant speed downhill. That implies no acceleration, and hence no force imbalance. So you need to find expressions for the forces involved. If you assume that the skier has a mass "m", what are expressions for the downhill force due to gravity and the frictional force?

Oh, and here's a ---> θ <--- for cutting and pasting :smile:
 


i posted the solution but knowing the rules had to delete it:
giving you a hint:
if velocity is constant; net force = 0
just equate all forces in it
 

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