Hi everyone ! I´m posting as I couldn´t find any information on the forum, or maybe I can´t find a way of searching. My question is based on a discussion me and my girlfriend had about "making yourself heavier", and we tried a little experiment: First I lifted her in my arms without any problems, and then I tried a second time while she "applied downwards force" or "tried to make herself heavier" and obviously was harder to lift. She claimed that the second time she tried to "anchor" down, but I insisted that was impossible since she could not add "weight" or increase the downwards force without acceleration. It´s kind of complicated to explain, but I´ll try to draw something to make more sense ! If anyone quite understood my point, all interpretations will be welcome ! Thanks !