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MHT CET202020 Oct 2020Evening ShiftPhysicsRotational MotionActual

Let a force F =- F k acts on the origin of cartesian frame of reference. The moment of force about a point (1,-1) will be

Options

  1. A- F ( + )
  2. B- F ( - )
  3. CF ( - )
  4. DF ( + )

Correct answer

D. F ( + )

Step-by-step solution

The point P lies at (1,-1) i.e, P = i - j PO = O - P =- P =- i + j Torque about point P : = PO F =(- i + j ) (- F k ) = F [( i k )+ k j ] Using: i j = k ; j k = i ; k i = j = F (- i - j )=- F ( i + j )

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