posted by Alex .
A horse pulls upon a wagon, but according to Newton’s third law the wagon pulls back with an equal and opposite force upon the horse. Use a free-body diagram and show all the involved forces.
i posted this question before but i still don't get it. Could someone explain what forces are involved in this problem?
If there is not acceleration, then net force must be zero. How can it be zero if something is pulling? ANS: something (friction?) is pulling back equal and opposite, so there is zero acceleration.