where , F is the force vector , and r is the vector from the axis of rotation to the point where the force is acting . where Ï is the torque vector and Ï is the magnitude of the torque , r is the displacement vector ( a vector from the point from which torque is measured to the point where force is applied ) , and r is the length ( or magnitude ) of the lever arm vector , F is the force vector , and F is the magnitude of the force , Ã -- denotes the cross product , Î is the angle between the force vector and the lever arm vector .