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

A particle of mass m moves in a circle of radius r. The angular momentum about the centre is:

Answer: mvr.

  • A mvr
  • B mv²r
  • C mr²v
  • D mv/r

Correct answer: A. mvr

Explanation: L = r × p = mvr (when v is perpendicular to r, as in circular motion). Also L = Iω = mr² × (v/r) = mvr.

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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