Friction in rotational motion..

[hamidace]

Hi. Could anyone please tell me what is the formula and how do we calculate the maximum velocity that a car can have while moving in a curve with a radius of R with a certain frictional constant in order to avoid sliding? Thank you.

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[Tan008]

set up a digram and label all your forces. Friction (if the car is moving) will be pointing towards the centre (if it's a banked curve then it will be pointing towards the centre but down the incline). Set up your axes anyway you feel comfortable (the forces you should have are mg, N, friction, and the centripetal force). Use F = mv^2/r to find velocity.

 

[hamidace]

Thank you. But I was thinking that the friction is tangent to the curve, maybe I'm wrong. . So the total force would be: F = F(friction) + mv^2/r or should the friction force be equal to the centripital force? I am still a little bit confused and would appreciate more explanation

 

[Tan008]

I am having a hard time trying to explain it without a good diagram, but I did find this for you. Check it out, it makes it pretty clear http://www.rit.edu/~jdasps/jdainfo/311_tp/BankedCurveFriction.html

 

[ACD]

You would be better served moving on to something that actually has a chance of being on the MCAT. Something like that would almost certainly be passage-based.

 

[hamidace]

I am having a hard time trying to explain it without a good diagram, but I did find this for you. Check it out, it makes it pretty clear http://www.rit.edu/~jdasps/jdainfo/311_tp/BankedCurveFriction.html

Thank you. This was really helpful.

To ACD: I took the MCAT and there was a similar question there in the discretes (unfortunately) and I did not know how to solve it

 

[ACD]

Thank you. This was really helpful.

To ACD: I took the MCAT and there was a similar question there in the discretes (unfortunately) and I did not know how to solve it

Wow, more and more everyday I feel like I got really lucky with my examination. I would have bombed that one for sure.

 

[Tan008]

you said that question was one of the descretes...for some reason i thought it was part of a passage.

 

[hamidace]

yep, it was one of the discretes. Pretty hard for a discrete, wasn't it?

 

[Tan008]

YES! very involved question. I thought for sure it was part of a passage. eek