Hello, I'm self studying physics right now and have learned about Newton's laws. However, I am confused by the first law. I understand that when the net force is 0, an object will continue its original motion at the same velocity. But how does this work for an airplane which is moving at a constant speed? Since it is going at a constant speed, the net force on the airplane is 0, right? Well, how do we then conclude that the airplane is moving forward, though logically that makes sense?