Newton's first law of motion is also referred to as the law of inertia. 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 same speed and in the same direction unless acted upon by an unbalanced force." Below is the formula to find force based on law.
If we threw a package out of an flight, it will continue to move at the speed of the airplane on the same direction of the airplane's movement. Since the law of gravity acts on the package and it gathers speed along the vertical axis, but on the horizontal axis its speed will remain equal to that of the flight.
Fact: This newton's first law is true according to modern physics. Galileo discovered the law during the first decade of the seventeenth century, but in fact he did not understand the law in the general way. The general formulation of the law of inertia was devised by Galileo's pupils and by Descartes - a French philosopher, mathematician and physicist. This law is also the first of Newton's three laws.