How Many Laws Of Motion Are There

There are three laws of Motion

Newton's laws of motion provide a rational connection between the forces acting on a body and the resulting changes. The laws of motion were established by Sir Isaac Newton in his work "Principia Mathematica Philosophiae Naturalis", published in 1686.

These are the Three Laws of Motion:

• Newton's first law of motion asserts that “if a body is at rest or travelling in a straight line at a constant speed, the state of motion of the body will not change unless and until an external force acts upon the body.”

• “The rate of change of a body's momentum is directly proportional to the load acting on it, according to Newton's second law of motion, and the momentum change takes place in the direction of the net force applied.”

• “Newton's third law of motion states that there will always be an equal and opposing reaction to every action.”

Newton's First Law Of Motion

The concept of inertia refers to the inherent quality of a physical object to maintain its present state, whether at rest or in motion. This principle was first introduced by Galileo Galilei, who applied it to explain the horizontal movement of the Earth. Later, the idea was expanded upon by René Descartes. Prior to Galileo, it was believed that a force was necessary to keep an object in motion. However, Galileo discovered that an object would remain in its current state unless acted upon by an external force, such as friction.

Without force, the state of motion or rest cannot be altered. Until an outside force is applied to halt it, a body travelling in a certain direction will continue to move in that direction.

Newton's Second Law Of Motion

The second law of Newton provides a numerical description of force. A body's momentum equals the sum of its mass and velocity. In a sense, momentum is a vector quantity with both magnitude and direction. When force is applied, a body can change its momentum, velocity, or both. One of the most significant rules of traditional physics is Newton's second law of motion.

The formula for Newton's law is as follows for a body of constant mass m:

F = ma,

Where "F" denotes the applied force, "a" represents the produced acceleration, and "m" represents the mass of the object.

A body accelerates if the net force acting on it is positive(i.e. in the body's direction of motion). In contrast, if there is no net force, there is no body acceleration.

When two objects with different masses are subjected to the same force, the second law of motion states that various accelerations (changes in motion) will result. Less massed bodies accelerate more quickly.

Comparing the impact of the same force applied to move a car with that of a football, the impact of a force of about 15 Newton on the football will be substantially greater. The two objects' different masses account for this variation.

Newton's Third Law Of Motion

Newton's third law of motion states that there is always an equal and opposite reaction to every action. Additionally, the action and reaction take place in two distinct bodies. When two bodies come into contact, they exchange forces with the same magnitude but in different directions. This equation has broad applications for both objects moving uniformly at an accelerated pace and static equilibrium (where the forces are balanced).

Real-life Examples Based On Applications Of Laws Of Motion

• Moving your study table from one half of the room to the other requires exerting force.

• When a laptop is placed on a table, it exerts a downward force equal to its weight, and the table responds by exerting an equal and opposing force. This force is present because the table is slightly deformed by the weight of the laptop, pushing the laptop back in response.

• When a car suddenly stops, the passengers inside it continue to move forward due to their inertia until the seatbelt or airbag provides a force to stop their motion.

• A soccer ball will not move unless someone kicks it, and it will continue to roll until it's stopped by force such as friction or hitting a wall.

• Pushing a heavy object requires more force than pushing a light object with the same acceleration.

• A car with a more powerful engine will accelerate faster than a less powerful one (considering other things as constant).

• When a person jumps off a diving board, the board pushes back the person with an equal force, propelling them into the air.

• When a rocket propels gas out of its engines, the gas pushes back the rocket with an equal and opposite force, propelling it forward.