Your 3.90 kg physics book is next to you on the horizontal seat of your car. The coefficient of static friction between the book and the seat is 0.660, and the coefficient of kinetic friction is 0.560. Suppose you are traveling at 90.0 km/h = 25.0 m/s and brake at a constant rate to a stop over a distance of 80.4 m.
(a) Will the book start to slide over the seat? yes no
(b) What force does the seat exert on the book in this process? It is ............... upward and backward at .......... ° with the horizontal.