Torque As A Vector Cross Product

As presented in NCERT Class 11, Chapter 7 (System of Particles and Rotational Motion), torque is defined as the vector cross product τ = r × F, whose magnitude is given by rF sinθ, where θ is the angle between the position vector r and the applied force F. Being a cross product, the torque depends only on the component of the force that is perpendicular to the position vector, since the cross product extracts exactly that perpendicular contribution. The direction of the torque is given by the right-hand rule, perpendicular to the plane containing r and F. When the force is parallel to the position vector, the angle between them is θ = 0°, so sinθ = 0 and the torque magnitude is exactly zero, because a purely radial force exerts no turning effect about the origin. The option 'Maximum' applies only when the force is perpendicular to the position vector, that is θ = 90°, not parallel. The option 'Equal to rF' would require sinθ = 1, which again is the perpendicular case and not the situation described. The option 'Equal to r + F' is dimensionally meaningless, since one cannot add a length to a force. A consistency check confirms that a purely radial force cannot rotate a particle about the very point it points toward, so a torque of exactly zero is the physically correct answer.