Physics: Principles with Applications (7th Edition)

Published by Pearson
ISBN 10: 0-32162-592-7
ISBN 13: 978-0-32162-592-2

Chapter 9 - Static Equilibrium; Elasticity and Fracture - Questions - Page 250: 14

Answer

See solution.

Work Step by Step

Stress$=\frac{F}{A}$ Because area is constant, as force increases, stress increases. To calculate the force on the lower spinal column, we can write the net torque equation by including the force of the weight of the arms, upper body, and head into consideration. Even though the weight and distance from pivot point (hip) are equal, the lever arm for each force when standing upright and bending down is larger, creating a greater torque about pivot point. Therefore, greater force, and therefore greater stress, is required by the lower spinal column to keep the body in equilibrium position. See image for a stick figure of a person in upright and sitting positions.
Update this answer!

You can help us out by revising, improving and updating this answer.

Update this answer

After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.