Maybe I should ask you about how you feel weight. Well let me say that what you are feeling right now isn’t really gravity. For example stand on an elevator. Do not push the buttons. Just stand there while the elevator is at rest. How do you feel? Because you are at rest and staying at rest, your'e in equilibrium.
And if your acceleration is zero, then your net force must also be zero.
Two forces you feel are the force of the floor pushing up and gravitational interaction with the Earth pulling downward. The magnitudes of those forces must be equal in order for the net force to be zero.If you push the up button during the "ride" the elevator accelerates upwards, which might make you feel Anxious or maybe even heavier.
If you're accelerating upwards, then the net force must also be upwards. Using the same two forces, there are two ways this can happen. The floor can push MORE on you, or the Earth can pull LESS. Since the gravitational force depends on your mass, the Earth’s mass and the distance between the two,doesn’t change. So, the floor must push harder on you.And you feel heavier but the gravitational force is the same. If You are going to the top floor and then elevator has to stop. Since it was moving up, but slowing down it must accelerate in the downward direction.Now the net force must be in the downward direction. Again, the gravitational force's magnitude doesn’t change. The only thing that can happen is for the floor to push less. which makes you feel lighter.Suppose the elevator cable breaks and the elevator falls. In this case, it's acceleration will be -9.8 m/s2. How much would the floor have to push up on the person to accelerate down at -9.8 m/s2? It wouldn’t have to push at all. The force the floor exerts on you would be zero. How would you feel? You would feel scared – I mean you are in an elevator with the cable cut. How else do you think you would feel? Well, maybe you could be scared AND hungry if you were late for lunch or something. Oh, you would feel weightless.
