If each orange book on the bookshelf makes a 70° angle with the base of the shelf, we can infer that the books are tilted. However, without more context or a diagram it's challenging to say anything more specific about the orientation or arrangement of these two orange books. If this scenario pertains to a stacking problem, the students may be concerned with the stability of the stack. To estimate how many books could be stacked before the pile tumbles, they would need to know the mass of each book, the width of each book, and the depth of each book.
When it comes to moving the bookshelf or lifting books, the amount of work done plays a role. For instance, when lifting a book onto a shelf, the work done against gravity depends only on the height of the shelf and the mass of the book, not on the path or time taken. When moving a heavy object like a bookshelf, understanding the shear modulus can describe how the material deforms under force, and this would be relevant for the scenario involving the cleaning person pushing a heavily-loaded bookcase.
Therefore Final answer is angle at which the orange books are placed suggests they are tilted, but further information is needed to determine their stability as part of a stack. Knowledge of the mass, width, and depth of the books would be required to estimate how many could be stacked without tipping