Question 12
Why is it easiest of all to move a go cart by pushing it from behind and pulling it from the front at the same time?
The right answer is the one marked above.
They add, because both point the way the cart has to go. The resultant of the two forces is then at work.
Pushing behind while pulling in front is not applying forces in opposite directions — the two people stand on opposite sides of the cart, but both forces point forward. Only in a tug of war are the forces genuinely opposed.