Question

suppose you your writing this is tilted a book kept on it starts sliding down so the direction of frictional force acting on it​

Answer 1

When a book slides on the writing desk, a frictional force acts between the book and the surface of the desk. The direction of frictional force on the book is opposite to the direction of its motion and acts in upward direction, as shown in the figure alongside

Answer 2

Answer:

opposite to the direction of you are writing