samsingh

is true but some how i do dissagree

your discussion is kind of good but it is a force because its that force which makes lighter mass aclerate.how can gravity be acleration when 2 equall mass bodies are allowed to freefall they will have the same speed or velocity and same acceleration because f=ma

can supersonic aircraft have vertical takeoff:cool:

you see when the 1mm metal is inside it will be attracted by electric magnet

i think ri can be negative