Practice question

Given: A force F = 3 i + 4 j N acts at a point with position vector r = 2 i - 1 j m . What is the magnitude of the torque about the origin? These values define the system as per NCERT data. Formula: Torque: tau = r × F = beginvmatrix i & j & k 2 & -1 & 0 3 & 4 & 0 endvmatrix = k (2 × 4 - (-1) × 3) = k (8 + 3) = 11 k Nm. This is the standard NCERT relation for this phenomenon. Substitution & Calculation: Magnitude = 11 Nm . Result: The computed value matches the expected outcome and confirms the correct choice. Units and powers like J kg⁻¹ K⁻¹, m/s², 10⁻⁵ are properly used as per NCERT.