Chapter4: Statics - Torques and equilibrium
Download as PPT, PDF9 likes5,065 views
This document discusses chapter 4 on statics from a textbook. It covers topics like torques, equilibrium of rigid bodies, center of gravity, stability and balance, levers and mechanical advantage. It provides examples of these concepts and how they apply to both engineering structures and biological structures like jaws, limbs, and backbones. Levers in the human body are discussed, like how muscles in the jaw and head act as levers. Sample problems are provided to calculate forces using information about levers.
Chapter4: Statics - Torques and equilibrium
- 1. Chapter 4: Statics ()علم السكون Torques and Equilibrium ()العزوم و التزان
- 2. Outline Torques ()العزوم Equilibrium of Rigid Bodies () توازن الجسام الجاسئة-الصلبة Center of Gravity ()مركز الثقل Stability and Balance ()الستقرار و التوازن Levers; Mechanical Advantage ()الروافع: الفائدة اللية Muscles ()العضلت Levers in the Body (الروافع في جسم الكائنات )الحية The
- 3. Introduction Statics is the study of the forces acting on an object that is in equilibrium and at rest. Engineering structures: Bridges or buildings Biological structures : Jaws (,)الفك limbs( ,)اطرافor backbones(.)العمود الفقاري Engineering, comparative anatomy(تشريح ,)مقارنphysical therapy( ,)العلج الطبيعيand orthodonture (.)تقويم السنان
- 4. Torques
- 5. Torque
- 6. Examples
- 7. Conditions for a rigid body equilibrium:
- 8. Types of equilibrium: static equilibrium: a state of equilibrium in which the net external force and torque acting on a system is zero dynamic equilibrium: a state of equilibrium in which the net external force and torque on a system moving with constant velocity are zero
- 9. Example
- 10. Example 2
- 12. Example Unlike most of the other muscles in our bodies, the masseter muscle()العضلة الماضغة in the jaw, as illustrated in next slide, is attached relatively far from the joint, enabling large forces to be exerted by the back teeth. (a) Using the information in the figure, calculate the force exerted by the teeth on the bullet. (b) Calculate the force on the joint.
- 13. A person clenching a bullet between his teeth
- 14. Solution
- 15. Lever in Human Body
- 16. Lever in Human Body
- 17. Lever in Human Body
- 18. Lever in Human Body
- 19. Lever in Human Body
- 20. Lever in Human Body
- 21. Glossary torque: turning or twisting effectiveness of a force perpendicular lever arm: the shortest distance from the pivot point to the line along which F lies SI units of torque: newton times meters, usually written as N·m center of gravity: the point where the total weight of the body is assumed to be concentrated
- 22. Exercise 4-13 Find the force F1 and F2 on the tooth in fig. 4.36 (In orthodonture, forces applied to the teeth lead to forces on the supporting bones, Gradually the bone tissue breaks down and permits the tooth to rotate or translate. New bone tissue grows in the space left behind. The forces must be small enough to avoid damaging the root of the tooth.
- 24. Solution
- 25. Exercise 37 The head pivots about the atlanto-occipital joint (Fig.4.46). The splenius muscles attached behind the joint support the head. (a) What class of lever does this represent? Class 1 (b) The anterior muscles ()العضلت الماميةproduce forward motions of the head. What class of levers does their action represent? Class 3