Main Question or Discussion Point
I'm confused about how it is possible for speed to be constant when a centripetal force is being applied to an object. If something is orbiting a planet, when it is at what one person considers the top of the planet, all of the objects velocity is in the horizontal direction, and all of the acceleration is in the vertical direction. I would think that this would result in the object gaining speed. Even as it starts to move and gain an acceleration in the direction opposite its motion I would think that the vertical acceleration is increasing the speed faster than the horizontal is decreasing the speed.