## The Auto-Mechanics of Newton’s Laws of Motion

Sir Isaac Newton gained notoriety for his discovery of gravity after watching an apple fall from a tree. Newton also documented the fundamental laws of physics, a set of principles that describe how and why things work in the physical universe. Newton expanded on the previous ideas established by his predecessors that described the dynamics of motion. The laws of motion include the fundamental principles of inertia, acceleration, and interaction. He never neglected to give credit where it belonged. In fact, he was quoted once for stating that his work “stood on the shoulders of giants.” The laws of motion paved the way for man to walk on the moon, build exciting amusement parks, and led to the development of the automobile.

The First Law of Motion: The Law of Inertia

The law of inertia states that an object at rest remains in the same place. Newton’s first law of motion also states that an object in motion stays in motion with the same speed and direction it started unless it originated from an unbalanced force. In other words, stationary objects will always remain at rest, while movable objects continue on their course without changing pace. If a car travels with an eastward velocity of 10 mph, then it will continue in the same state of motion. If the car travels with a westward velocity of 20 mph, it will continue at that same rate of motion. The only time an object deviates from this forward motion is if an unbalanced force interferes with its pace. All objects resist changes to their pace of motion.

The law of inertia can apply to any situation involving stationary or movable objects. Consider any personal traveling experiences in an automobile. For instance, a cup of water filled to rim stays stationary until the driver accelerates the car causing an unbalanced forward motion. The water remained at rest; however, pushing the cars accelerator caused the water to move and spill out of the cup. If the driver suddenly applies the brakes, then the water continues moving forward at the same speed and direction it started when the car first accelerated. Water in motion stays in motion. The same applies for passengers who originally sat stationary before the driver placed his or her foot on the accelerator. The passengers start their forward motion and continue at the same speed and direction, regardless if the driver applies the brakes. Seat belts act as the only unbalanced force that prevents passengers from flying out of the windshield.

The Second Law of Motion: The Law of Acceleration

Newton’s second law of motion explains the direct relation between the mass of an object and the net force applied during acceleration. The law of acceleration states that the mass of an object determines its resistance to movement. This means that the greater mass of an object impedes the overall rate of acceleration. In addition, the greater force of an object aids in the increasing rate of acceleration. For example, a pebble has a smaller mass than a boulder, so it will accelerate faster than its counterpart. Pushing a boulder by hand yields greater resistance than using a backhoe, which exerts more force on the boulder, enabling it to move faster than when manually pushed by hand.

All stationary objects maintain equilibrium, a condition of balanced forces, and will not accelerate. In accordance with the law of inertia, a boulder that rests remains at rest until an unbalanced force induces its movement. Therefore, Newton’s second law only applies to objects with an unbalanced force. The mathematical expression of Newton’s second law reads as “F=MA,” or force equals mass times acceleration. It can be applied to the physics of an automobile. For example, Audrey runs out of gas on the highway in her economy-sized sedan that weighs roughly 1,000 kg. Audrey pushes the car to the nearest gas station at 0.05 m/s/s. Audrey can compute how much force she should apply to move the car using the mathematical expression governed by the law of acceleration. The answer should come to 50 newtons (F=1,000×0.05).

The Third Law of Motion: The Law of Interaction

The law of interaction explains the interaction between multiple objects. Newton’s second law of motion forms the basis that every action produces an equal and opposite reaction. When one car collides with another, it exerts a force on that car, even if its at rest. Both cars have opposite forces that move in different directions from each other. As an individual jumps in the air, he or she must exert force to push away from the ground. Both forceful exertions by the individual and ground interacts to cause an upward movement against gravity.

Using the law of interaction, Newton derived the core principle implicating the conservation of momentum. This law states that the momentum of a system remains constant if no existing external forces acts on the system. This embodies Newton’s first law of inertia. In addition, the law of interaction can be seen using the second law of motion. For instance, when an object applies force against a secondary object at some point of contact, it must cause an equal and opposite force that cancels the initial force. If there were a net force on a mass-less point, then it would accelerate the initial point of contact ad infinitum.

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