Calculating coefficient of static friction without a mass.by Gheret Tags: curves, force, friction, without mass 

#1
Mar3011, 05:54 AM

P: 11

1. The problem statement, all variables and given/known data
A car is travelling at 30m/s around a bend of radius 70m. What coefficient of static friction between the tires and the road is required to ensure the car will not slip? 2. Relevant equations 3. The attempt at a solution I know that the centripetal acceleration is a=30^2/70 and I know that this acceleration has to be canceled out by the frictional force for the car to not slip, but I am not sure out to calculate frictional force F=mA without a mass for the car. 



#2
Mar3011, 06:15 AM

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P: 40,880

(Tip: Solve things symbolically as much as possible. Only use the calculator at the end.) 



#3
Mar3011, 07:16 AM

P: 11





#4
Mar3011, 07:29 AM

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P: 40,880

Calculating coefficient of static friction without a mass. 



#5
Mar3011, 07:38 AM

P: 11

I'm sorry but I am totally lost now..
What I have done so far: F(r)=mv^2/r=F(fr) F(r) being centripetal force and F(fr) being frictional force. But I do not know the equation for calculating coefficient of static friction. Thanks for helping me out. 



#6
Mar3011, 07:44 AM

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P: 40,880





#7
Mar3011, 07:47 AM

P: 11

Oh I was completely ignoring normal force!
F=u(9.8m/s^2)m mv^2/r=u(9.8m/s^2)m (30)^2/70=u(9.8) Right? 



#8
Mar3011, 07:49 AM

Mentor
P: 40,880

Right!
(This assumes that the road is flatno banking angle.) 



#9
Mar3011, 07:51 AM

P: 11

You have been the best help.
Thank you for not just telling me the answer cause now I have actually learnt how to solve these for myself. Thank you! 


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