Answer:
Third and fourth diagrams correctly represent the forces as vectors.
Explanation:
The vehicles are pulling against each other, this means their force vectors must point in the opposite directions, so our diagram must have this property.
Looking a the first diagram we see than both force vectors point in the same direction, so this cannot be the right answer.
In the second diagram the force vectors have the same direction, but in direction opposite the previous diagram. This is also not a correct diagram for our situation.
In the third diagram the forces vectors point in the opposite directions and they have the right magnitudes ( 750N is smaller than 1000N vector). So this diagram correctly represents our situation.
For the fourth diagram the vectors point in the opposite directions and they have the right magnitudes; therefore, it is also a correct representation of the situation.
So we have got two correct diagrams: the third and fourth. And we cannot choose between them because we do not know whether it's the truck or the car that is on the left or right. For example if the car was on the left the third diagram would have been chosen.
