Equilibrium Of A Rigid Body Moments And Center Of Gravity
Equilibrium of a rigid body, moments, and center of gravity
Equilibrium Conditions
- For an object to be in equilibrium, the net force and net torque acting on it must be equal to zero.
Center of Gravity (CG)
- The center of gravity (CG) of an object is the point where the entire weight of the object is considered to be concentrated.
For a symmetric object, the CG is at its geometric center.
- The CG of a system of particles is the point where the total torque due to the weights of the particles is zero.
Methods for finding the CG
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For symmetric objects: the CG can be determined by inspection.
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For objects with simple shapes: the CG can be calculated using formulas.
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For irregular objects: the CG can be determined by the principle of moments.
Stability
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A body is in stable equilibrium if, when slightly disturbed from its equilibrium position, it tends to return to that position.
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A body is in unstable equilibrium if, when slightly disturbed from its equilibrium position, it tends to move away from that position.
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The stability of a body depends on the position of its CG.
An object is most stable when its CG is lowest.
