Not necessary be. Depend on how big is that vacuum box. If the box is big enought up to a point the overall resultant density of that box is smaller than that of same volume of ground surface air, the box will float up.
Not necessary be. Depend on how big is that vacuum box. If the box is big enought up to a point the overall resultant density of that box is smaller than that of same volume of ground surface air, the box will float up.