Acceleration has 2 definitions.
Zero has value
A speed + Zero is not division by 0
A net force is not a new force, it just means no additional force
Oh yeah and gravity is a lie - at least the way most understand it
I totally agree with Noam Chomsky that most are taught stupid, especially Americans whom have no idea where to even begin questioning what they are taught and think they can google something and know the truth in 2 seconds. I think school should be ended, people dont need to learn , they can just google stuff and google will always explain things to you. <--------irony.

Because that's just how physics works. If the Earth was moving at a constant speed upwards, any objects on it would be moving at that same speed and conserve their momentum. To fall they would have to start moving slower than the Earth, but why would they?
It's the same as flying on an airplane. When the plane is in the air and moving at 500 mph, you can freely move around inside of it and you feel no force pushing you towards the rear of the plane. In other words, you don't "fall" towards the rear.
Likewise, if you are in a car, you only experience the acceleration of it. When you give gas, you are pressed against the seat (falling into it), but when the car is moving at a constant speed on a highway you don't feel anything.

It was the "every thing would fall" part if the earth doesn't change its velocity vector. ie: if gravity doesnt excist. You guys are on the same page

Neat, within this topic this experiment makes me realize that the buoyancy of the medium (in this case air) effects the value "g". and is therefore one of the least constant constants used in mechanics

/e: ofc buoyancy alone doesn't replace gravity.. just effects the forces needed for levitation . (seems so logical when you think of it.. But air density can change quite a bit ^^)

This post was edited by Knaapie on Nov 2 2016 10:24am

a constant same change in vector to me would seem linear, it's just added value to the vector. I'm sure top-end physicists know how to calculate the vector of a perfect sphere, and I doubt they would term it as constantly "accelerating". Idk, physics isn't my thing, but a simple change in vector would seem like taking it too literally, that it accelerates. It's a simple change in direction, must be an odd convention.

The mass of the planet doesn't provide gravity , the curving of space time does, thanks Einstein for crushing Newton!


This post was edited by card_sultan on Nov 2 2016 10:32am

A constant change is what we see as a constant acceleration/deceleration in a certain constant (perpendicular) direction.

This does not make sense to me. The reason why objects fall towards Earth is because Earth attracts those objects through gravitational force. The direction of an object's velocity compared to the direction of Earth's velocity does not matter, as the object will undergo an additional acceleration towards Earth regardless.

Your analogy concerning cars and airplanes does not make sense either. Our body does not follow the plane/car's movement because of gravity; it does so because the car/plane seat pushes us forward with the same speed the airplane is traveling. Once our velocity equals that of the plane/car (which is almost immediately), the net acceleration of our body is zero, and we simply follow the plane/car without experiencing any force. No, scratch that; we do experience a force: a downwards one, towards Earth. Ta-dah, gravity.

But let's disregard that. If what you say is true, then why does gravity suddenly appear when Earth's movement vector does change?

could be wrong but i think you're missing that flat earth theorists hold that the earth is travelling upward constantly and that's what causes "gravity" which they believe doesn't exist.

that's Einstein's relativity.. Even he isn't completely right, but explains what we perceive as gravity on a different scope..
Do you want to try to disprove relativity with quantum physics ? ^^