Newton's Laws

Newton’s Laws of Motion

First Law – The Law of Inertia

• Inertia is the property of an object that resists changes in its state of motion. This is the central part of Newton’s First Law.
• Newton’s First Law states that an object will remain at rest or move in a straight line at a constant speed unless acted upon by a net external force. This is often termed as the principle of inertia.
• A net external force refers to the total magnitude and direction of all forces acting on an object.

Second Law – Force, Mass and Acceleration

• Newton’s Second Law describes how the velocity of an object changes when it is subjected to an external force.
• The law states that the acceleration of an object is directly proportional to the net force exerted and inversely proportional to its mass. In other words, F=ma.
• This means that an object’s acceleration, or its change in motion, is equivalent to the force applied divided by the object’s mass.

Third Law – Action and Reaction

• Newton’s Third Law states that for every action force, there is an equal and opposite reaction force.
• This means that any force exerted on a body will create a force of equal magnitude but in the opposite direction on the object that exerted the first force.
• It’s important to remember that these force pairs act on different objects, not the same object.

Implications of Newton’s Laws

• Newton’s Laws form the foundation of classical mechanics and are widely used to analyse the motion of everyday objects and systems.
• Understanding these laws can also help in understanding more complex physics concepts, like momentum and energy.
• Practical applications of these laws can be found throughout engineering and science, including areas like vehicle safety design and space travel.