How exactly is a bottle cap opened/closed? To open/close one, it needs to be rotated and simultaneously translated upwards/downwards for it to move up/down its thread and not be translated right or left alongside.
From my understanding, for this, I’d need to apply an equal and opposite force so the cap doesn’t slide right or left and provide torque for it to rotate. How does this make it move up/down? It must be because of the thread somehow but how exactly?
And for an equal and opposite force, I need to use two fingers, how can I be so precise so as to apply equal and opposite forces with my fingers? And how is it possible to open/close a cap with one finger then? Then I’d have no equal and opposite force and the cap should translate right or left? Does it being constrained to the bottle neck prevent that? So the bottle neck applies a normal equal and opposite to the force my finger applies and that prevents sliding right or left?
(I’m new to this, my notions are probably wrong or very basic.)