Here's why:

* Balanced forces: Balanced forces are equal in magnitude (strength) and opposite in direction. They cancel each other out, resulting in no net force. This means an object at rest stays at rest, and an object in motion continues at a constant velocity.

* Forces in the same direction: When two forces act in the same direction, they add up. The net force is the sum of the individual forces. This means there is a net force acting on the object, causing it to accelerate in the direction of the forces.

Example:

Imagine pushing a box with a force of 10 N to the right. If another person pushes the box in the same direction with a force of 5 N, the net force on the box is 15 N to the right. The box will accelerate in that direction.