CHAPTER 12

Newton’s Second Law, Fnet = ma

IN THIS CHAPTER
Summary: Chapter 10 explained how to deal with objects in equilibrium, that is, with zero acceleration. The same problem-solving process can
be used with accelerating objects.

Key Ideas
Only a NET force, not an individual force, can be set equal to ma .
Use a free-body diagram and the four-step problem-solving process when a problem involves forces.
When two masses are connected by a rope, the rope has the same tension throughout. (One rope = one
tension.)^1
Newton’s third law: force pairs must act on different objects.

Relevant Equations

Um, the chapter title says it all ...

What this means is that the net force acting on an object is equal to the mass of that object multiplied
by the object’s acceleration . And that statement will help you with all sorts of problems.

The Four-Step Problem-Solving Process

If you decide that the best way to approach a problem is to use F (^) net = ma , then you should solve the
problem by following these four steps.