Hi, I have been looking everywhere for an answer on what weight actually is so I joined the Physics Forum as it looks very promising. I have looked in many many places for a definition of the weight force and get completely different answers so I am now very very confused. All the textbooks I read along with websites seem to say that weight is the gravitational pull on a mass and is calculated as: W = mg (it also acts down) That was all fine until I watched an undergraduate MIT lecture where the professor said that weight is the reaction force from the ground. If there is no ground beneath you (freefall) then "your weight is zero by definition" is the lecturers exact words and he seemed very explicit about this being the true definition of weight. Wikipedia also states there are these two conflicting views of what weight actually is. These two definitions both have flaws along with the fact they contradict each other. If weight is the reaction force from the ground then free body diagrams must be wrong as the convention for these diagrams is that the weight force is acting down. On the other hand if weight really is the product of the gravitational field and mass then the notion that scales measure your weight must be completely wrong. For example, if you are in free fall with some scales attached to your feet then they will read zero which means your weight is zero according to MIT but how can it be according to W= mg as you still have g and you still have mass! So I guess my two main questions are: 1) When you are in freefall do you have weight or not? 2) Do scales really measure your weight? I ask this because if you are in freefall then according to W = mg you still have a weight but since the scales read zero then scales must surely not measure your weight by this definition. If anyone can kindly help with my confusion I will be eternally grateful!!!