Balanced and Unbalanced Forces:-

Newton's first law of motion states that "an object at rest stays at rest and an object in motion stays in motion with the similar speed and in the same direction unless acted upon by an unbalanced force."

But what exactly is meant by the phrase unbalanced forces?

Let's consider a physics book at rest on a tabletop.

There are 2 forces acting upon the book:

1) Earth's gravitational pull - exerts a downward force.

2) The push of the table on the book - normal force - that pushes upward on the book.