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MHT CET202522 Apr 2025Morning ShiftPhysicsMathematics in PhysicsActual

If force F =-3 i + j +5 k acts along r =7 i +3 j + k then the torque acting at that point is

Options

  1. A(14 i -38 j +16 k )
  2. B(-14 i +34 j -16 k )
  3. C(21 i +4 j +4 k )
  4. D(4 i +4 j +6 k )

Correct answer

A. (14 i -38 j +16 k )

Step-by-step solution

The torque is given by the cross product = r F with F = -3 i + j + 5 k and r = 7 i + 3 j + k . Computing the determinant: = vmatrix i & j & k 7 & 3 & 1 -3 & 1 & 5 vmatrix = i (15 - 1) - j (35 + 3) + k (7 + 9) = 14 i - 38 j + 16 k This result corresponds to option A .

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