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⚛️ Physics  ·  System of Particles and Rotational Motion  ·  NEET & JEE

A rigid body is in rotational equilibrium. This means:

Answer: Net torque acting on it is zero.

  • A Net torque acting on it is zero
  • B Net force is zero
  • C Both net force and net torque are zero
  • D Angular momentum is changing

Correct answer: A. Net torque acting on it is zero

Explanation: Rotational equilibrium requires Στ = 0. For complete (static) equilibrium, both ΣF = 0 and Στ = 0 are needed.

axis OPr⊥Fττ = r⊥ × F = r × F × sinθ

Torque about axis O equals the force F multiplied by the perpendicular distance r⊥ from the axis to the line of action of the force, producing rotation.

Concept context

Moment of inertia, torque, angular momentum, rolling motion. Very high JEE weightage.

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