(i) We know that,
Moment of force = Force ร Perpendicular distance
We can see from the given figure that vector C has least perpendicular distance from point O.
Hence, vector C will have least moment about O.
(ii) We know that,
Moment of force = Force ร Perpendicular distance
We can see from the given figure that vector A has the greatest perpendicular distance from point O
Hence, vector A will have the greatest moment about O.
(iii)(a) Clockwise moments are produced by vectors A and B.
Reason: If the turning effect on the body is clockwise then a moment of force is called a clockwise moment and it is taken as a negative value.
(b) Anticlockwise moment is produced by vector C.
Reason: If the turning effect on the body is anticlockwise then the moment of force is called an anticlockwise moment and it is taken as a positive value.
(iv) Sum of torques due to vectors A, B and C = Resultant torque about point O
= -(4 ร 0.9) – (4 ร 0.8) + (4 ร 0.6) N m
= -3.6 – 3.2 + 2.4
= -4.4 m
So, the resultant torque is 4.4Nm (clockwise direction).