How does mg = ma follow from F=ma?

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Newton's second law, F=ma, indicates that the net force acting on an object equals its mass multiplied by its acceleration. In the specific scenario where gravity is the only force, this can be expressed as mg=ma, leading to the conclusion that g=a, meaning the acceleration of an object in free fall is equal to the acceleration due to gravity. However, real-world situations often involve additional forces like air resistance and friction, complicating the application of F=ma. Therefore, the equation typically represents the sum of all forces acting on an object. Understanding these principles is crucial for grasping the dynamics of motion.
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Can somebody explain in simpler terms F=ma and why that can be writtent as mg=ma. Which finally can be written as g=a.
 
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memsces said:
Can somebody explain in simpler terms F=ma and why that can be writtent as mg=ma. Which finally can be written as g=a.
Newton's 2nd law states that the net force on an object must equal ma. In the special case where the only force on an object is gravity, which equals mg, then the net force is just mg. Thus mg = ma, which implies that g = a. (The acceleration of an object in free fall is g downwards.)
 
Doc_al is correct in saying that g = a when the object is in free fall (the only force acting on the object is gravity). However the world is not that simple, there are a lot more forces that can act on objects such as support force, air resistance, friction just to name a few. So therefore F=ma means the sum of all forces = ma, usually seen with the symbol sigma (meaning the sum of forces) before F. I hope that clarified things for you memsces.
 

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