What is that strange feeling when you stop in an elevator or drive over a quick hill?
The feeling over a quick hill is a negative G force. You become (partially) weightless because as you go down hill the reaction from the ground pushing up becomes reduced and so you are in momentary free fall, similar to when astronauts orbit the Earth and become weightless. Since it is over so quick so don’t get time to adjust and so the feeling is quite strange. The same occurs when you start to descend in a rollercoaster or very fast elevator or experience tubulnece in a plane that forces the plane down quickly. The feeling when you stop in an elevator is similar. When the elevator starts, you have a slight feeling of increased weight as the reaction of the floor pushing up is greater than the force of gravity pushing down because the lift is accelerating upwards and so the total force upwards is greater than the total force downwards. When the forces become balanced, you ascend at a constnt speed, but as the elevator stops, the force downwards (gravity, basically unchanged) becomes
