Car on unbanked curve

  • Thread starter akatsafa
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  • #1
akatsafa
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I'm setting this problem up, but I'm now stuck.

A car is safely negotiating an unbanked circular turn at a speed of 17m/s. The maximum static frictional force act on the tires. Suddenly a wet patch in the road reduces the maximum static friction force by a factor of three. If the car is to continue safely around the curve, to what speed must the driver slow the car?

I made a free body diagram and came up with f net equations. I have fnetx=1/3usg=v^2/r. I have fnety=N-mg. For fnetx, I further get 3.267m/s^2us=v^2/r. And this is where I get stuck. I'm not sure what I do to find the speed without knowing the radius.
 

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  • #2
arildno
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The magnitude of the initial frictional force satisfies:
[tex]F=m\frac{v_{0}^{2}}{R}[/tex]

Afterwards, we have:
[tex]\frac{1}{3}F=m\frac{v_{1}^{2}}{R}[/tex]

By division, we get:
[tex]\frac{1}{3}=(\frac{v_{1}}{v_{0}})^{2}[/tex]
 

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