# Banked curve with friction, but no angle

## Homework Statement

A banked curve has been designed so that it is safest for a vehicle going 70 mph. The topography of the land restricts the radius of the road to 300m. Assume mu(static friction) is 0.80 and mu(kinetic friction) is 0.60.
A 5512 lb vehicle travels with a speed of 60 mph on the curve.
1. Calculate the force that the road exerts on the vehicle.
2. Calculate the friction on the tires.

## Homework Equations

F=ma
Centripetal acceleration=v^2/r

## The Attempt at a Solution

converted all mph's given to m/s and converted weight in lbs to N.
tried to find the angle by:

v^2/r=Wsinθ

I came up with 19.45 degrees. This just doesn't seem right, that's an awfully steep bank.

Related Introductory Physics Homework Help News on Phys.org
Doc Al
Mentor
tried to find the angle by:

v^2/r=Wsinθ
How did you arrive at this? Note that the units do not match: The left side is an acceleration, while the right is a force.

I was wrong in that angle. I found the correct angle by assuming no friction, solving the y force for Fn and substituting it in the x force equation. This gave me theta.
Then, after figuring out the x y axis could be rotated to go with the Fn on the car, solved like any other incline plane problem.