Engineering a highway curve. If a car goes through a curve too fast, t

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Engineering a highway curve. If a car goes through a curve too fast, the car tends to slide out of the curve. For a banked curve with friction, a frictional force acts on a fast car to oppose the tendency to slide out of the curve; the force is directed down the bank (in the direction water would drain). Consider a circular curve of radius R = 220 m and bank angle θ, where the coefficient of static friction between tires and pavement is μs. A car (without negative lift) is driven around the curve as shown in the figure below. Find an expression for the car speed vmax that puts the car on the verge of sliding out, in terms of R, θ, and μs. Evaluate vmax for a bank angle of θ = 11∘ and for (a) μs = 0.77 (dry pavement) and (b) μs = 0.047 (wet or icy pavement). (Now you can see why accidents occur in highway curves when icy conditions are not obvious to drivers, who tend to drive at normal speeds. ) (a) Number Units (b) Number Units

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R = 220 m

and bank angle

θ

, where the coefficient of static friction between tires and pavement is

μ_{s}

. A car (without negative lift) is driven around the curve as shown in the figure below. Find an expression for the car speed

v_{max}

that puts the car on the verge of sliding out, in terms of

R, θ

, and

μ_{s}

. Evaluate

v_{max}

for a bank angle of

θ

= 11^{\circ}

and for (a)

μ_{s} = 0.77

(dry pavement) and (b)

μ_{s} = 0.047

(wet or icy pavement). (Now you can see why accidents occur in highway curves when icy conditions are not obvious to drivers, who tend to drive at normal speeds.) (a) Number i Units