A book is resting on a board. One end of the board is slowly raised. The book starts to slide when the incline angle is 15°. What is the coefficient of static friction between the book and the incline? This is an AP Physics 1 Topic.

Content Times:
0:01 The example
0:44 Drawing the free body diagram
1:41 Net force in the parallel direction
2:11 Demonstrating why the acceleration in the parallel direction is zero
3:58 Force normal does not equal force of gravity
4:32 Net force in the perpendicular direction
5:07 Return to the parallel direction
6:06 Substituting in numbers
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