# Homework Help: An unbanked and a banked curve

1. Sep 26, 2008

### lpcampbe

A car can negotiate an unbanked curve safely at a certain maximum speed when the coefficient of static friction between the tires and the ground is 0.84. at what angle should the same curve be banked for the car to negotiate the curve safely at the same maximum speed without relying on friction?

Okay, so my professor hasn't gone over this in lecture. I have already done a problem kind of similar to this one with banked curves, except I was trying to find the "safest speed" of the car to go around a curve with a radius of 130 m that was banked at 3 degrees. But I don't even know where to start with this problem because all I know is the static friction is 0.84. And I know that I'm trying to find out the angle the curve should be banked for the car to make it around at the same speed but with no friction.

2. Sep 26, 2008

### tiny-tim

Hi lpcampbe!

Start by working out what the speed is …

you need to compare the centripetal acceleration with the force of friction.

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