Conceptual Physics (12th Edition)

Published by Addison-Wesley
ISBN 10: 0321909100
ISBN 13: 978-0-32190-910-7

Chapter 2 - Think and Discuss: 84


If you jump heavily onto your feet from an elevated position, your spine will tend to compress. At the end of the day, after your body has jostled up and down from walking, and felt the effects of gravity, you will be a tiny bit shorter.

Work Step by Step

The bones in your spine, which are in motion just before you land, tend to stay in motion when you land, so they will compress the elastic disk spacers, just as the hammerhead is tightened onto the handle in Figure 2.5. This is discussed on page 26. The disks can plump up again and the bones can separate while you sleep horizontally, and so you regain your height each morning. On the other hand, note that nocturnal creatures, such as Dracula or some college students, find themselves shorter in the early morning after their activity period, and taller in the evening after they have slept all day.
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