Please provide a rating, it takes seconds and helps us to keep this resource free for all to use
Welcome to our Physics lesson on Newton's Second and Third Law and Systems of Reference, this is the fifth lesson of our suite of physics lessons covering the topic of Relativity. Galilean Transformations. Einstein's Postulates and Newton's Laws, you can find links to the other lessons within this tutorial and access additional physics learning resources below this lesson.
If a particle in an inertial system of reference is accelerated, i.e. if it does not perform a standard motion, we say the particle interacts. A force F⃗ - which measures the intensity of interaction - acts on the particle. On the other hand, the acceleration a⃗ the particle experiences, gives the intensity of particle's deflection from the standard motion. As explained in Section 4, the relationship between these two quantities is given by the Newton's Second Law of Motion.
Hence, it is clear that the acceleration a particle experiences due to the action of a force is proportional to the force itself. This statement represents the Newton's Second Law of Motion expressed in words. Here, 1/m is the coefficient of proportionality, which turns the given proportion into equation and the mass itself expresses the inertia, i.e. the tendency of an object to resist to any change in its state of motion.
Newton's Third Law of Motion (the action-reaction principle) completes the framework of Newtonian Dynamics. It says: "For every action, there is an equal-size but opposite reaction".
In this way, it is clear that when the net force acting on an object is zero, the object moves in standard mode (i.e. at constant velocity). Since it is practically impossible to find any free particle in Earth conditions, we can obtain inertial systems of reference only if the net force on an object is zero, as this situation is more realistic.
If we neglect some factors such as air drag, friction, etc., the system connected to the Earth can be considered more or less as a good inertial system of reference. A flying airplane when no air turbulences are present, is also a good inertial system of reference as well as the system connected to the Sun. However, the best model of an inertial system is the one connected to a spacecraft moving into the interstellar space with the engines tuned off.
You have reached the end of Physics lesson 18.1.5 Newton's Second and Third Law and Systems of Reference. There are 5 lessons in this physics tutorial covering Relativity. Galilean Transformations. Einstein's Postulates and Newton's Laws, you can access all the lessons from this tutorial below.
Enjoy the "Newton's Second and Third Law and Systems of Reference" physics lesson? People who liked the "Relativity. Galilean Transformations. Einstein's Postulates and Newton's Laws lesson found the following resources useful:
Please provide a rating, it takes seconds and helps us to keep this resource free for all to use
We hope you found this Physics lesson "Relativity. Galilean Transformations. Einstein's Postulates and Newton's Laws" useful. If you did it would be great if you could spare the time to rate this physics lesson (simply click on the number of stars that match your assessment of this physics learning aide) and/or share on social media, this helps us identify popular tutorials and calculators and expand our free learning resources to support our users around the world have free access to expand their knowledge of physics and other disciplines.