Theory:

Consider you are trying to move a box. Will you move the box without touching it?

A boy pushes the box

The answer will be no. It is not possible, right! So in order to push or pull an object, there should be a physical interaction. The box moves away when the boy pushes the box, and it moves towards the boy when he pulls the box. The direction of force decides the direction of movement of an object.

Women fetches the water from a well

In the above image, a woman pulls the rope. It causes the pot to move upwards, and thus she can able to fetch the water. In this case, the direction of force is opposite to the movement of an object. But we learnt that the objects move in the direction of applied force. The reason for this is due to the presence of a pulley that is fixed at a particular point above the well. The pulley changes the direction of the applied force.

Girls pulling each other

In the above case, who is pulling whom?

Both of them pull each other. So, in this case, the direction of movement will be along the direction of greater force. Thus, the movement will be along with the person who applies a greater force.

From the above examples, we can finalize that at least two objects should interact to bring force between them. Therefore, the interaction of one object with another results in the force between the two objects.