Question

if something is in side a container is weightless how could I tell what the is inside? and isn't mass and weight different?

Answer 1

Think about mass, each of the objects have a different set of mass (mass is different from weight). If we applied an acceleration to each of the boxes (lets say pushing it), we can see which one would show a bigger "Force" when it comes in contact with another object (say another person to feel that force).