The Defining Qualities of a Free Particle

I wanted to talk about the mathematical description of a plane wave and why it is how it is. A free particle, you can imagine a free particle, as just a ball rolling on a floor that is just perfectly level. This analogy is used because there is no ike gravitational potential change. In this case, if you were to roll the ball up a ramp, then the kinetic energy would give way to the potential energy as it goes up the ramp,. But if there's no ramp, the floor is just, we're assuming no frict nthe flourish is flat.