Getting "Left Behind"

On Saturdays I usually have a riding lesson, which is always the highlight of my weekend. On my drive home from the barn, I was reflecting on the lesson and what I could improve on for next week. The goal of riding is to make all your cues to your horse invisible and move with the horse as much as possible. Sometimes, after asking for a faster speed from their horse, a rider gets "left behind"- as the horse gets faster the rider doesn't move with the horse and look like they aren't moving together. It can happen when the rider asks and is off balance or unprepared for the change or sometimes, as in today's case, you are riding a young (in the horse world it's called "green") horse. The horse I was riding today, Mystic, decided a few times to go a little bit faster than I had anticipated so I got left behind. After taking him over some ground poles at a trot, he started cantering (a faster speed than a trot). I could have helped him by making my clues more clear. In any case, on my drive home, my reflections turned to the physics of the matter. An object in motion wants to stay in motion, initially. When riding, two objects are trying to act as one, but when the horse changes speeds abruptly, the rider continues to move at the previous speed causing him or her to get "left behind". It's sort of like when you step on the brakes of the car and come to a stop really quickly, your body lurches forwards because it's trying to move at the same speed as it was before. The seat belt keeps you in place. With riding, it just works in the opposite direction with your body moving slower and the horse moving faster. And there is no seat belt keeping you on