Newtons 3rd law+Horse Cart System+Action/Reacton..help needed ASAP!!!!!!! im a sophmore in the ib program and i'm in conceptual physics i have a test tommorow on newtons third law and all the stuff that goes along with it.. so i need an answer on this pronto! first of all.. if you are standing still.. is the considered an action/reaction force? i thought it was.. because the earth exerts a force up on you and you exert a force down on the earth..? but for some reason, my friend said it wasn't.. and i dont know..? then i have a question on the horse-cart system.. idk if you know of this but its an example found in alot of textbooks.. and it shows a horse attatched to a cart and the horse says 'I cannot accelerate this cart because the forces are equal and opposite of me and the cart and will cancel to zero'.. well i know thats not true.. but why.. and i also need to know.. a)what makes the cart accelerate b)what makes the horse accelerate c)what makes the horse-cart system accelerate i need someone who KNOWS for SURE about this.. please do not give me a bogus answer and make me fail my test tommorow!