25. D Before attempting this problem, review Examples 7 and 8. Two curves on a highway have the same radii. However, one is un- banked and the other is banked at an angle 0. A car can safely travel along the unbanked curve at a maximum speed vo under conditions when the coefficient of static friction between the tires and the road is µ, = 0.81. The banked curve is frictionless, and the car can nego- tiate it at the same maximum speed v,. Find the angle 0 of the banked curve.

In 1959, Daytona Speed was added to the NASCAR racing circuit and introduced 31° banked curves for racing. This allowed stock cars to reach much higher speeds (around 200 mph) during a race. Today the steepest banked curves are found at Talladega Motor Speed Way at 33° with a turn radius of 1100 ft. The flattest track in NASCAR is Hew Hampshire Motor Speed Way with banked curves of 7° with a turn radius of 410 ft. a) Assuming no friction, what are the max speeds (in mph) without slipping toward the outer edge of the track at the Talladega and NH Motor Speedways? b) With friction (assume μs of 1.1 between the tires and the track)?

A car drives around two circular curves on two different roads. The two curves have the same radius of curvature. And coincidentally, the maximum speed that the car can drive through either of the turns is the same for both roads. The first road is frictionless, but it is banked at 14.5 degrees from the horizontal. The other turn is flat. What is the coefficient of friction between the car tires and the road on the unbanked turn?

A jet flying at 130 m/s banks to make a horizontal circular turn. The radius of the turn is 3810 m, and the mass of the jet is 1.86 × 105 kg. Calculate the magnitude of the necessary lifting force. L -