Sir Isaac Newton: Unveiling the Secrets of Motion

A prodigy of mathematics and physics, Sir Isaac Newton forever changed the landscape of science with his groundbreaking laws. In 1666, at the age of 23, Newton introduced the laws of gravitation. In 1686, he presented his three laws of motion in the iconic "Principia Mathematica Philosophiae Naturalis."

Newton’s First Law: Inertia

Newton’s first law, often referred to as the law of inertia, is a cornerstone in understanding the fundamental principles of motion. It states that an object at rest will remain at rest, and an object in motion will persist at a constant speed in a straight line unless acted upon by an unbalanced force. This innate resistance to changes in motion is known as inertia. When external forces balance out, leaving no net force, the object maintains a steady velocity.

Examples of inertia in the realm of aerodynamics:

• The motion of an airplane adjusting its throttle setting.

• A falling ball navigating through the atmosphere.

• The launch of a model rocket into the atmosphere.

• The movement of a kite responding to changes in the wind.

Newton’s Second Law: Force

Newton’s second law delves into the relationship between force, mass, and acceleration. Simply put, the acceleration of an object is directly proportional to the force applied and inversely proportional to its mass. The law is expressed mathematically as F = m * a, where F is force, m is mass, and a is acceleration.

Applying Newton’s second law to aerodynamics:

Consider an airplane at point "0" with mass m0, velocity V0, and an external force F acting on it, moving it to point "1" with new values m1 and V1. The change in momentum, m * V, allows us to determine the new values of V1 and m1 based on the force F.

Newton’s Third Law: Action & Reaction

The third law of motion is a poetic dance between interacting objects. It declares that for every action (force) in nature, there is an equal and opposite reaction. If object A exerts a force on object B, object B retaliates with an equal and opposite force on object A.

Real-world examples of action and reaction in aerodynamics:

• Lift generated by an airfoil, where air is deflected downward, causing the wing to be pushed upward.

• A spinning ball deflecting air to one side and, in turn, moving in the opposite direction.

• The thrust produced by a jet engine, with hot exhaust gases streaming out, resulting in a thrusting force in the opposite direction.

Reviewing Newton’s Laws of Motion

1. Newton’s First Law of Motion (Inertia): An object at rest remains at rest, and an object in motion remains in motion at a constant speed and in a straight line unless acted on by an unbalanced force.

2. Newton’s Second Law of Motion (Force): The acceleration of an object depends on the mass of the object and the amount of force applied.

3. Newton’s Third Law of Motion (Action & Reaction): Whenever one object exerts a force on another object, the second object exerts an equal and opposite force on the first.

By embracing Newton’s laws, we unravel the secrets of motion and aerodynamics, propelling our understanding of the universe and the celestial bodies within it.