Banked Curve "perfectly banked" 1. The problem statement, all variables and given/known data if a curve with a radius of 88. is perfectly banked for a car traveling 75km/h, what must be the coefficient of static friction for a car not to skid when traveling 95km/h? 2. Relevant equations ƩF=ma and a=v^2/r and Ff=μFn 3. The attempt at a solution below is my attempt but i also want to know what they mean when they say "perfectly banked" is that a specific angle or a specific coefficient of friction? because i can't seem to get anywhere. a=752/88 Fnx=Fnsinθ, Fny=Fncosθ, Ffx=Ffcosθ, Ffy=Ffsinθ. in the x-direction: ƩF=ma Fnx+Ffx=ma Fnsinθ+μFncosθ=m(752/88) (88Fn(sinθ+μcosθ))/752)=m in the y-direction ƩF=ma Fny-Ffy-Fg=ma (no acc in y-dir) Fncosθ-μFnsinθ=mg (Fn(cosθ-μsinθ))/g=m set the 2 equations equal to each other: (88Fn(sinθ+μcosθ))/(752)=(Fn(cosθ-μsinθ))/(9.8) (Fn divides out) (88)(9.8)sinθ+(88)(9.8)μcos=752(cosθ)-752(μsinθ) common factor, take sin and cos out of brackets on both sides, divide: tanθ=(752-(88)(9.8)μ)/(752μ+(88)(9.8) and that's as far as i got help me please!