How many uniform, identical textbooks of width 25.0 cm can be stacked on top of each other on a level surface without the stack falling over if each successive book is displaced 3.00 cm in width relative to the book below it?

Question

If the books are 5.00 cm thick, what will be the height of the center of mass of the stack above the level surface?

Answer 1

divide width by displacement and add the 1st book.
25/3 = 8.33333 + 1 = 9 books

take the number of books form the 1st answer and multiply by the thickness of the books and then divide by 2. 9*5 = 45/2 = 22.5