Newton’s Laws of Motion. Forces. Newton’s First Law of Motion. What happens to a ball rolling along the ground? Why does it keep moving? What slows it down? What happens to a ball when it is thrown in the air? Why does a ball that is at rest stay where it is?. Newton’s First Law of Motion.
Let’s look at the horse and the cart in greater detail, with a free body diagram.
Force of Cart on Ground?
Force of Horse on Ground?
Force of horse on ground = force of ground on horse
Force of cart on ground = force of ground on cart