Equilibrium of Rigid Body
o A force changes the translational state of the motion of the rigid body , i . e . it changes its total linear momentum .
o A torque changes the rotational state of motion of the rigid body , i . e . it changes the total angular momentum of the body
Note : Unless stated otherwise , we shall deal with only external forces and torques .
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A rigid body is said to be in mechanical equilibrium , if both its linear momentum and angular momentum are not changing with time . This means
Total force should be zero => Translational Equilibrium Total torque should be zero => Rotational Equilibrium