Question 2.CE.1: Force diagram for a book Book A sits on a table with book B ......
Force diagram for a book
Book A sits on a table with book B on top of it. Construct a force diagram for book A.
Sketch and translate We sketch the situation below. We choose book A as the system object. Notice that the dashed line around book A passes between the table and book A, and between book B and book A. It’s important to be precise in the way you draw this line so that the separation between the system and the environment is clear. In this example, Earth, the table, and book B are external environmental objects that exert forces on book A.
Simplify and diagram Draw a force diagram for book A, which is represented by a dot. Two objects in the environment touch book A. The table pushes up on the bottom surface of the book, exerting a force \vec{F}_{\text {T on } A} and book B pushes down on the top surface of book A, exerting force \vec{F}_{\text {Bon } A} . In addition, Earth exerts a downward force on book A \vec{F}_{\operatorname{Eon} A} .
Try it yourself: Construct a force diagram for book A assuming that another book C is placed on top of book B.
Answer: The same three objects interact with book A. Earth exerts the same downward force on book A \left(\vec{F}_{\text {E on } A}\right) . C does not directly touch A and exerts no force on A. However, C does push down on B, so B exerts a greater force on A \left(\vec{F}_{\mathrm{B} \text { on A }}\right) . Because the downward force of B on A is greater, the table exerts a greater upward force on book A \left(\vec{F}_{\mathrm{T} \text { on A }}\right) .
