From Pottermore - Extension Charms we get this quote:
These spells not only increase the interior dimensions of objects, while leaving the outer ones unchanged, they also render the contents lighter.
My question is more based around where and when the objects are lighter and if they experience this themselves.
For instance it is obvious that when lifting an Extension Charmed item filled with heavy objects the entire collection of objects is lighter, at least from the outside.
So when a person enters an ECed (Extension Charmed) tent does that person become lighter inside of the tent or just to forces outside of the tent? Equally are objects inside an ECed item lighter whilst you interact with them when you are inside? I.E picking up a bed whilst inside a tent as oppose to picking up the tent with the bed inside. Or would it all be relative? So that when you enter the tent you become lighter but also weaker so everything would seem just as heavy as normal.
It seems obvious to me that a tent (basically a huge bag) would render it's contents lighter including people.
- Would accept a physics answer