car moving along a banked curve with friction (solved) first off, thanks to whoever helps me. you're a life saver. i could just copy it from a friend, but i want to be skilled enough for the AP Physics B exam. so yeah... i just want to understand what i have to do. the logic with this is killing me. ok here's the problem: A 1200-kg car rounds a curve of radius 67m banked at an angle of 12 degrees. If the car is traveling at 95 km/h, will a friction force be required? If so, how much and in what direction? ok, here's what i got so far. first, i converted 95 km/h to 26.388... m/s. then, i found a formula in the book for things with no friction required: tan (theta) = (v^2)/(rg). so i plugged in the angle, radius, and gravity constant to see what speed would be necessary for no friction required. i got 11.8 m/s. nowhere near. so i now have that friction is required. simple enough. so now i need to find out how much friction force is needed. i drew a diagram to help me figure out how weight, normal force, friction force, and centripetal force are related as vectors. i understand centripetal force and weight are constant in this case. i know i have to find the friction force as a vector since the coefficient of friction isn't provided, so i can't find it directly from normal force. thing is though, normal force and friction force affect each other, and i have no clue how to figure out normal force in this case. i tried messing around with the vectors and solving for friction force by pythagorean theorem, sin, and cos, but i ended up getting three different answers... i am massively confused. assistance would be GREATLY appreciated.