why is it more difficult to walk in sand than on an wooden path?
Answers
Although I wont get into the nit and grit, (Pun intended, Dx) sand is difficult to walk and run in because of the shifting solid under you, this shifting solid makes the ground seem like it is moving beneath you (Cause it is, to a small extend)
It also forces you to exert more effort to move, see for every action there is an equal or opposite reaction, on solid ground this means that the grass, stone, packed dirt, or really anything solid is getting pushed away, but it can’t move very far without great effort, so this motion gets pushed back onto you for a greater force. While on sand, the ground can move causing less force to be rebounded towards you (Not really what happens but it makes it easier to understand) , so when you push off, some of the ground you were using to support yourself gets pushed away rather than staying in place, this takes away force causing you to not go as far.