What is the connection between friction and thermal energy plz

Why is there friction between objects

Awoman holds a book by placing it between her hands such that she presses at right angles to the front and back covers. the book has a mass of m = 1.8 kg and the coefficient of static friction between her hand and the book is μs = 0.67. no attempt 50% part (a) what is the weight of the book, fgb in newtons?

For the car in the picture ,in which direction is the normal force? -into the screen -down -out of the screen -up