Hi. I'm having some trouble trying to grasp a concept. I know that mathmatically Force perpendicular to motion is zero work. I can't seem to grasp this conceptually. First It seems That is an object is moving right and a force acts straight up on it, it will cause the object to move in a up/right path, thus causing work. This came up when my book started to talk about orbital energies and escaping an orbit. It talked about how you must apply a force in the tangential direction to cause an object in orbit to go to a higher orbit. The book said that you can't apply a force in the radial direction because it is perpendicular to the motion of the object. Again, here I don't se why it won't do work. It should still cause the craft to move farther out and into a higher elliptical orbit. Can someone hlp me understand this?