Hello. I've got three doubts I can't solve by myself: ¿which is the force a horse must make with its hoofs to start a movement forward, and what force is needed to slip?. And the third question is what is the diagram of forces in these two cases?.
Newton's laws, force of friction (fe max=μeFn), normal force (Fn), force of gravity (Fg), and horse's applied force(Fh).
The Attempt at a Solution
I Know that two horizontal forces are involved: the force made by the horse, and the friction of the ground. But I really don't know how to apply Newton's third law, and explain whose are these two forces' reaction forces; and I don't know to argue when does the horse start movement, and when does slip.