TORQUE DEFINED

1. TORQUE DEFINED • a Force applied a system restricted to moving in a circular path • causes a system/body to rotate • the Point of Application is eccentric • T = F x FA

2. MUSCLE TORQUES • Magnitude - product of F x FA • Direction - angle of pull on bone • Line of Action - vector direction • Point of Application - attachment to bone

3. FA: FORCE ARM • shortest distance from axis of rotation to the line of action of the applied Force • (perpendicular) to line of action

4. TEETER-TOTTER • Axis of Rotation • 2 Forces • 2 Force Arms

5. FIG E.8 Page 116 of textbook

6. FIG 9-30 “Basic Biomechanics” 3rd Edition Susan J. Hall

7. CALCULATING TORQUE • Force measured in Newtons [4.45N = 1Lb.] • Force Arm measured in meters • Torque measured in Newton meters [Nm]

8. FIG E.11 page 118 • sum up all Torques on each side of axis • side of axis with the larger  of T determines direction of movement

9. Angular Motion Vectors • there are both kinetic and kinematic vectors • A vector is represented by a straight line arrow symbol • the length of the arrow is the magnitude • the orientation of the arrow is the direction • to get a straight line vector for angular motion, the right hand thumb rule is used

10. RIGHT-HAND THUMB RULE • method of determining vector direction for angular motion • curve fingers of right hand in the direction of the Torque • right thumb points in vector direction of the motion, to the actual direction of the spin

11. Right-Hand Thumb points in vector direction FIG 15.9on page 506 FIG 15.10on page 507

12. CENTER of BUOYANCY • the location of the C of G of the volume of water displaced by a immersed body • body’s CB must be aligned with body’s CG for floating to occur