Fundamentals of Physics

What causes roller-coaster headache?

Roller coasters are designed to give the illusion of danger (that is part of their fun), but in fact engineers go to extreme lengths to make them exceedingly safe for riders. In spite of this attention to passenger safety, an unlucky few of the millions of people who ride roller coasters each year end up with a medical condition called roller-coaster headache. Symptoms, which might not appear for several days, include vertigo and headache, both severe enough to require medical treatment.

The answer is in this chapter.

Fig. 10-1 Figure skater Sarah Hughes in motion of (a) pure translation in a fixed direction and (b) pure rotation about a vertical axis.

10-1 What Is Physics?

As we have discussed, one focus of physics is motion. However, so far we have examined only the motion of translation, in which an object moves along a straight or curved line, as in Fig. 10-1a. We now turn to the motion of rotation, in which an object turns about an axis, as in Fig. 10-1b.

The number of times you encounter rotation in everyday life may be uncountable. You see it in nearly every machine, you use it every time you open a beverage can with a pull tab, and you pay to experience it every time you go to an amusement park. Rotation is the key to many fun activities, ...