Newton's 1st Law of Motion
Do you know that when the dogs are stopped by something like a tree or when the musher stops them it is Newton's 1st Law of Motion coming to life? Newton's first law of motion states that an object in a state of rest or uniform motion will remain in that state unless an external force is applied. The musher applies a force to make them stop by pulling on the ropes and the trees obviously stop them 'cause they put a greater froce on the dogs if they run into them, but normally the musher will stop them before it's too late.