Suppose you find yourself teetering on the edge of a cliff or the roof of a tall building with a heavy physics book in your hand. As you are about to fall, you suddenly remember how physics can save you! What law did you remember?

Answer: Law of Conservation of Momentum

Explanation:

According of Law of Conservation of Momentum:

"If the result of the forces acting on a body or system is null, its linear momentum remains constant in time ".

In fact, this law is actually a direct consequence of Newton's third law of motion:

"When two bodies interact between them, appear equal forces and opposite directions in each of them."

To understand it better:

Each time a body or object exerts a force on a second body or object, it (the second body) will exert a force of equal magnitude and direction but in the opposite direction on the first.

So, if you If you throw the heavy physics book forward, you will have a backward momentum (with the same magnitude and opposite direction), hence a backward force that will make you fall to the side of the building and you will not fall over the edge.