Steepest slope before slipping

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Homework Statement


The coefficient of friction between the trains wheel's and the rail on a frosty day is 0.1, What is the steepest slope (expressed in the form ''1 in n'') that the train can climb without slipping.

train.jpg



Homework Equations



Ff = μ(Fn)

The Attempt at a Solution



I have no idea. Don't want a solution, just a little guidance would be much appreciated. I understand that the point where the train will begin to slip is when the maximum friction force is reached but I can't see how to apply this to this question.
 

Answers and Replies

  • #2
LowlyPion
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OK. You've got the force of friction.

If it's on an incline what force must it at least match in order to go uphill?
 
  • #3
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The force must be at least equal to the natural force. what I've attempted so far, I found the frictional angle to be 5.71o, by tan-1(0.1*N/N). now i'm lost.
 
  • #4
LowlyPion
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The force must be at least equal to the natural force. what I've attempted so far, I found the frictional angle to be 5.71o, by tan-1(0.1*N/N). now i'm lost.
The statement says:
(expressed in the form ''1 in n'')
Maybe they just want it as a 1 in 10 rise or more precisely as a rise of 1 /(102 + 1)1/2 = 1 in 10.05 rise?
 
  • #5
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The statement says:

Maybe they just want it as a 1 in 10 rise or more precisely as a rise of 1 /(102 + 1)1/2 = 1 in 10.05 rise?
That would make sense, as the answer I think is 57o, but just out of curiosity how did u come to that conclusion, as it is not in the question do u just have to assume this. Freshmen to physics so excuse my ignorance if i am missing something obvious. Thanks for your help by the way.
 
  • #6
LowlyPion
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That would make sense, as the answer I think is 57o, but just out of curiosity how did u come to that conclusion, as it is not in the question do u just have to assume this. Freshmen to physics so excuse my ignorance if i am missing something obvious. Thanks for your help by the way.
Your 5.7° answer is correct of course. I was merely noting the form that they want the answer in.

Physics is also a matter of English when it comes to supplying the answer in the right form.

So how did I come to the conclusion ...? I guess I'd say it is a careful reading of the problem. As much as anything your course may encourage you to read with precision every bit as much as understanding equations.
 

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