Lets say i want to make a car that opens its door while the car is moving.If i weld the car and the door , will the door move with the car AND open ? If no , then what should i use?
Yes, it can move depending on how you weld it and what method you are using. For example, if you write out a program and have a GUI or press a key to open a certain door, you can make it open using that way. As long as it is not anchored when the car is moving (if it was anchored it was even then prevent the car from moving in the first place) then it should work no matter what.
It's more or less about the coding and how you go about writing your code. Hope this helps :P