CHAPTER 8

Extra Drill on Difficult but Frequently Tested Topics

IN THIS CHAPTER
Summary: Drills in five types of problems that you should spend extra time reviewing, with step-by-step solutions.

Key Ideas
Tension problems
Electric and magnetic fields problems
Inclined plane problems
Motion graph problems
Simple circuits problems

Practice problems and tests cannot possibly cover every situation that you may be asked to understand in
physics. However, some categories of topics come up again and again, so much so that they might be
worth some extra review. And that’s exactly what this chapter is for—to give you a focused, intensive
review of a few of the most essential physics topics.
We call them “drills” for a reason. They are designed to be skill-building exercises, and as such, they
stress repetition and technique. Working through these exercises might remind you of playing scales if
you’re a musician or of running laps around the field if you’re an athlete. Not much fun, maybe a little
tedious, but very helpful in the long run.
The questions in each drill are all solved essentially the same way. Don’t just do one problem after

the other ... rather, do a couple, check to see that your answers are right,^1 and then, half an hour or a few
days later, do a few more, just to remind yourself of the techniques involved.

Tension

How to Do It

Use the following steps to solve these kinds of problems: (1) Draw a free-body diagram for each block;
(2) resolve vectors into their components; (3) write Newton’s second law for each block, being careful to
stick to your choice of positive direction; and (4) solve the simultaneous equations for whatever the
problem asks for.