2.2.A.1–1.iiConcept
Forces are vector quantities that describe the interactions between objects or systems. A force exerted on an object or system is always due to the interaction of that object or system with another object or system, and an object or system cannot exert a net force on itself.
ExampleWhat pushes on the book?1 / 3
A book rests on a table. Identify the two objects involved in the force that holds the book up, and state which object exerts the force on which.
Try it on paper first, then reveal each step to check your work.
Step 1 — Identify the two objects
The force holding the book up is the normal force, and it requires two objects: the table and the book.