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4 FUNCTIONS of MACHINES Balance 2 or more Forces Force advantage

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Presentation on theme: "4 FUNCTIONS of MACHINES Balance 2 or more Forces Force advantage"— Presentation transcript:

1 4 FUNCTIONS of MACHINES Balance 2 or more Forces Force advantage
Linear ROM and/or Speed Change direction of F motive

2 3 Components of Levers Axis or fulcrum Motive Force Resistive Force

3 PROPERTIES OF A FORCE Magnitude Direction Point of Application
Line of Action

4 No Torque Net Torque Imbalance of Tm & Tr
resultant motion in the direction of the greatest Torque No FA example Fig 4.3d T motive = T resistive

5 FA resistive action line of gravity acting through lower arm’s c of g to axis of rotation (elbow joint) FA motive action line of muscle pulling on bone to axis of rotation (elbow joint)

6 Figure 4.4 on page 149 4.4a Tmotive = Tresistive  result is no motion
4.4b Tmotive > Tresistive  resultant motion is ccw 4.4c Tmotive < Tresistive  resultant motion is cw

7 Figure Question 2 page 151 if A = 100 weight units d must = 1.0 distance units if A = 40 weight units d must = 2.5 distance units

8 Resultant Torque Vector
Resultant Arrow represents Magnitude & Direction Resultant comprised of 2 components: 1. Ro = vertical/perpendicular component 2. Stabl or Disl = horizontal/parallel component

9 Position 1 more Stabl than Ro Position 2 100% Ro Position 3 more Disl than Ro
Figure 4.8 on page 154

10 Figure 4.10 on page 156 F1 = Stabl (pulls toward axis/joint)
FA for F1 =  d from axis to F1 F2 = 100% Ro (no horz component) FA for F2 =  d from axis to F2 F3 = Disl (pulls away from axis/joint) FA for F3 =  d from axis to F3

11 Figure 4.12b on page 157 Draw Resultant Motive Force Vector
Draw Resultant Resistive Force Vector Draw Motive and Resistive FA’s

12 FIG 4.12b page 157

13 Mechanical Disadvantage Advantage
FAMOTIVE < FA RESISTIVE LARGER FMOTIVE required to overcome SMALLER FRESISTIVE 3rd class levers FAMOTIVE > FARESISTIVE SMALLER FMOTIVE required to overcome LARGER FRESISTIVE 1st and 2nd class levers

14 1st Class Lever Axis/Fulcrum between MF and RF rare in human body
serves all 4 functions of machines

15 2nd Class Lever Axis at one end, Fmotive further away than Fresisitive
FAmotive > FAresisitive only serves 1 function of machines

16 3rd Class Lever Axis at one end, Fresisitive further away than Fmotive
FAmotive < FAresisitive only serves 1 function of machines

17 Wheel and Axle A machine that gives either a Force advantage OR a ROM advantage F advantage = Fmotive applied to wheel ROM advantage = Fmotive applied to axel in humans most common = ROM advantage


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