Car driving around a banked curve (with friction)

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Homework Help Overview

The problem involves a car navigating a banked curve with friction, specifically focusing on the maximum speed achievable without sliding. The context includes a concrete highway curve with a specified radius and angle, alongside the mass of the car and the coefficient of friction.

Discussion Character

  • Exploratory, Conceptual clarification, Problem interpretation

Approaches and Questions Raised

  • The original poster attempts to relate centripetal force and frictional force but expresses uncertainty about how to combine these concepts effectively. They question whether the normal force should include the angle of the bank.

Discussion Status

Participants are engaging in clarifying the forces at play and suggesting the use of a free body diagram to visualize the components contributing to the centripetal force. There is an indication of progress as one participant expresses newfound understanding after receiving guidance.

Contextual Notes

The discussion includes considerations of the static coefficient of friction and the angle of the bank, which may influence the interpretation of the forces involved. The original poster's previous experience with similar problems without friction is noted as a potential source of confusion.

TA1068
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Homework Statement


A concrete highway curve of radius 80.0 m is banked at a 13.0 degree angle.

What is the maximum speed with which a 1400 kg rubber-tired car can take this curve without sliding? (Take the static coefficient of friction of rubber on concrete to be 1.0.)


Homework Equations


F_r = \frac{mv^2}{r}

F_f = \mu N


The Attempt at a Solution


I have a few pieces here, but I'm not completely sure how to put them together.

There's a rotational force pulling towards the center of the circle:
F_r = \frac{mv^2}{r}
Where mass and radius are given.

Also, there is a frictional coefficient:
F_f = \mu N
Where \mu is 1.0 and N is mgcos\theta (at least I believe it is... or is it just mg?) where m, g, \mu, and \theta are given.

I had a relatively easy time understanding problems in which there was no friction, but I can't quite figure this out. Anyone have any advice to push me in the right direction? :)
 
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You already noted that the centripedal force is towards the center of the circle, so all you need to know now is which forces have a component pointing horizontally towards the center. I suggest that you draw a free body diagram with all the forces. This will help you see which contribute (and what components) to the centripetal force.
 
carbank.gif
 
Awesome... Thank you very much! It all makes sense now. I kept treating centripetal force as a force in itself instead of a net force. Thanks again!
 

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