Here's why:

* Balanced forces: This means the forces acting on the object are equal in magnitude and opposite in direction. They effectively cancel each other out.

* Newton's First Law of Motion: This law states that an object at rest will stay at rest, and an object in motion will stay in motion at a constant speed and direction unless acted upon by an unbalanced force.

* Net Force: Since the forces are balanced, the net force on the object is zero. A net force of zero means there's no change in the object's motion.

Example:

Imagine a book sitting on a table. Gravity pulls the book down, but the table exerts an equal and opposite force upwards. These forces are balanced, so the book stays at rest.