system
Given the following post, respond as if you're commenting on Reddit:
human
[portal/portal2] i was wandering, if i shot one portal on the ceiling and another on the ground, and was to dangle my foot over said portal and grab my foot, would i be able to pull myself up or if w ould free fall.
gpt
Any upwards force you imparted to yourself through your arm would be equal to downward force acting on your foot. If your other foot remained planted next to the ground portal, you would remain stationary, unable to rise because of the force of your hand pulling you down in addition to gravity. You would in effect be fighting your standing leg with your pulling arm. If you had the strength to overpower that leg, you would end up falling through the hole. If you sit, as another comment suggested, you would still be unable to climb up as the moment your body rose relative to your feet you would find yourself unsupported, and would fall.

Imagine lying on your back with your legs in the air, and trying to lift yourself up by crawling up your own feet.