Banked highway curves and static friction

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Homework Help Overview

The discussion revolves around a physics problem involving a car navigating a banked curve, specifically examining the need for frictional force while considering the car's mass, speed, curve radius, and banking angle.

Discussion Character

  • Exploratory, Assumption checking, Mathematical reasoning

Approaches and Questions Raised

  • The original poster attempts to apply equations of motion and forces but expresses confusion over their calculations, particularly regarding the friction force and its direction. Some participants suggest reviewing the relationship between friction and normal force, while others propose simplifying the problem by resolving forces along the slope.

Discussion Status

The discussion is ongoing, with participants exploring different interpretations of the problem and providing guidance on resolving the equations. There is no explicit consensus yet, but some productive suggestions have been made to clarify the approach.

Contextual Notes

Participants are navigating the complexities of banked curves and the role of friction, with some uncertainty regarding the application of the equations and the assumptions about forces involved.

joseg707
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Homework Statement


A 1200 kg car rounds a curve of radius 67 m banked at an angle of 12 degrees. If the car is traveling at 95 km/hr, will a friction force be required? If so how much and in what direction?


Homework Equations


F=ma
a=v2/r

The Attempt at a Solution


I don't know what I'm doing wrong with this problem. These are the two equations I have from them and when I try to solve I either get a huge number or a negative.

Ncos[tex]\theta[/tex]-Ffrsin[tex]\theta[/tex]-mg=0

Nsin[tex]\theta[/tex]+Ffrcos[tex]\theta[/tex]=ma

I'm positive that it needs friction force and I think it is in the direction of the center of curve, but I haven't figured out a way to solve. Can someone please help?
 
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Hey thanks! I think I found out what I was doing wrong. I didn't really take notice that the force of friction was equal to the friction coefficient multiplied by the normal force. Thank you very much!
 
joseg707 said:
Hey thanks! I think I found out what I was doing wrong. I didn't really take notice that the force of friction was equal to the friction coefficient multiplied by the normal force. Thank you very much!

I don't think you did.
Your equations were right but you need to solve for F by eliminating N.

By far the simplest way is to resolve || to the slope in the first place.
 

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