When two forces are acting on an object in the same direction, we combine them by adding them.

Here's why:

* Force is a vector quantity: This means it has both magnitude (size) and direction.

* Same direction: When forces act in the same direction, their magnitudes simply add up.

For example, if you push a box with a force of 10 Newtons to the right, and someone else pushes it with a force of 5 Newtons to the right, the total force acting on the box is 15 Newtons to the right (10 + 5 = 15).