* Newton's First Law: This law states that an object at rest will stay at rest, and an object in motion will stay in motion at a constant velocity, unless acted upon by an unbalanced force. This means that for an object to remain at rest, the forces acting on it must be balanced.

Forces acting on an object at rest along the vertical axis:

* Gravity: This is the force pulling the object downwards towards the center of the Earth.

* Normal force: This is the force exerted by a surface on an object, acting perpendicular to the surface. In the case of an object at rest on a horizontal surface, the normal force acts upwards, counteracting gravity.

Example: Imagine a book resting on a table.

* Gravity: The Earth pulls the book downwards.

* Normal Force: The table pushes the book upwards with an equal and opposite force.

Since these two forces are equal and opposite, they cancel each other out, resulting in a net force of zero on the book. This is why the book remains at rest.

Important Note: While there might be no net force along the vertical axis, there could be other forces acting on the object along the horizontal axis, such as friction. However, for an object to remain at rest, the net force in all directions must be zero.