Download - F4 ch2.9
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2.9: FORCES IN EQUILIBRIUM
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Forces in Equilibrium
•When an object is in equilibrium, the resultant force acting on it is zero.
•The object will either be
▫1. at rest ▫2. move with constant velocity.
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RESULTANT FORCE•A single force that represents the combined effect of two of more forces in magnitude and direction.
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Examples( Label the forces acted on the objects)
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Addition of Forces • Resultant force, F = ____ + ____
• Resultant force, F = ____ + ____
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STEP 1 •Using ruler and protractor, draw the two forces F1 and F2 from a point.
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STEP 2
•Complete the parallelogram
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STEP 3
•Draw the diagonal of the parallelogram. The diagonal represent the resultant force, F in magnitude and direction.
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Resolution of Forces
A force F can be resolved into components which are perpendicular to each other: (a) horizontal component , FX
(b) vertical component, FY
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Resolution of Forces
• Component of weight parallel to the plane
= mg sin θ • Component of weight
normal to the plane = mg cos θ
Fx = F cos θ Fy = F sin θ