My roommate and I are having trouble agreeing on how suction cups work.
Presumably, the ambient air pressure is the only thing which keeps the suction cup attached to the object.
When lifting an object with a suction cup (or a rigid chamber with air pumped out):
Given that the suction cup isn't physically affixed to the object, it can't apply any force to lift it.
How does pulling actually lift the object?
What dictates how much weight can be lifted?
If the object is touching the ground (so there's no air underneath it), can it be lifted? If not, can the suction cup be detached by pulling?
In practice, why does a rubbery suction cup work better than a rigid object (such as an inverted glass cup)?
Inside a rigid spherical shell (with gravity towards the center), presumably a suction cup can be used to hang a mass.
Yet, the air pressure is acting nearly uniformly on the sphere. How does the gravitational force on the mass get balanced out so the whole system doesn't move?