A circular curve of radius 150 m is banked at an angle of 15 degrees. A 750-kg car negotiates the curve at 85.0 km/h without skidding. a) what is the normal force on the tires exerted by the pavement. b) what is the frictional force exerted by the pavement on the tires?

Answer: a) 7.1 * 10^3 N; b) - 880 N directed out of the curve.

Explanation: In order to solve this problem we have to use the Newton laws, then we have the following:

Pcos 15°-N=0

Psin15°-f = m*ac

from the first we obtain N, the normal force

N=750Kg*9.8 * cos (15°) = 7.1 * 10^3 N

Then to calculate the frictional force (f) we can use the second equation

f=P sin (15°) - m*ac where ac is the centripetal acceletarion which is equal to v^2/r

f = 750 * 9.8 sin (15°) - 750 * (85*1000/3600) ^2/150 = - 880 N