Newton’s Second Law of Motion: F = ma

Newton’s Second Law of Motion: F = ma

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Professor Dave again, I want to tell you about Newton’s second law. We learned about Newton’s first law of motion, which tells us that an object will continue its state of motion unless acted upon by some net force. The second law continues from there, describing what will happen if some net force is indeed present, whether from internal or external forces. This law tells us that force is equal to mass times acceleration. This is summarized in the following equation, F=ma. What it means is that we can do quantitative calculations relating the magnitude of a force applied to an object, the mass of the object, and the magnitude of the acceleration that object will experience, and it shows the derivation of the Newton as the SI unit of force when we plug in 1 kilogram and one meter per second squared for mass and acceleration. There are a number of things we can say about this equation, which is tiny but powerful. First it means that heavier objects will require the application of greater force in order to achieve the same acceleration as lighter objects, with acceleration being equal to force divided by mass. If we want these objects of varying masses each to accelerate at one meter per second squared, these are the magnitudes of the forces that must be applied in order for the math to work out. This also means that the second law can be rephrased to state that the acceleration an object experiences will be directly proportional to the force applied and inversely proportional to its mass. It is important to note that the net force is the sum of all the forces acting on an object. If multiple forces are acting on an object, which is often the case, we will need to represent them all in a free body diagram and then add up all the vectors to find the net force, which will tell us the direction of the acceleration that will occur in response to the net force. This kind of vector addition allows us to make predictions about the motion of an object even when it is being pushed or pulled in a variety of ways. Since forces are vectors they can be split up into x and y components, which will be useful for doing calculations in certain scenarios that we will investigate later. Newton’s second law of motion has an incredible range of applications, as it can be applied to any force that exists and it describes the motion of all accelerating objects in the universe. We can even use it to do things like calculate the masses of faraway celestial objects, but for right now we will just stick to the basics, so let’s check comprehension. Thanks for watching, guys. Subscribe to my channel for more tutorials, support me on patreon so I can keep making content, and as always, feel free to email me:

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