Question 5
In which is the one case where the two forces must be subtracted to find the resultant?
The right answer is the one marked above.
When the forces act in opposite directions along one line. The resultant is then the difference between them, and its direction is that of the larger force.
In the first two cases — one line or two parallel lines, same direction — the forces are added. For inclined forces there is neither an addition nor a subtraction.