Pulling against each other
You will have seen a tug of war, the national game played at Sinhala new year festivals.
The people taking part divide into two groups and pull the rope in opposite directions. The rope then moves in the direction of the greater force, because the resultant force acts in the direction of the greater force.
Figure to be added
Applying forces the same way is better
When an object has to be moved in some direction and several forces are applied to it in that direction, the collective force is the sum of those forces. Applying forces in different directions usually means the force is not used effectively. A greater collective force is obtained only if the forces are applied the same way.
Dragging a heavy object
We know from experience that when dragging a heavy object along the ground it is easier done by pushing from behind and pulling from the front.
A go cart
A go cart used to carry small children can be moved either by pushing it or by pulling it from the front. Applying force from both sides is easiest of all, because the resultant of the two forces is then at work.
Do not confuse the two
Pushing the cart from behind while pulling it from the front is not applying forces in opposite directions. Both the push and the pull point the way the cart has to go, so they add. Only in the tug of war are the forces genuinely set against each other.
Now let us find the resultant of two forces acting along one line in opposite directions.