I was working on some side problems and came across one that confused me. Why is the magnitude of acceleration greatest at periapsis? I know that the a there is only centripetal a at that point. But if we look at another point, say theta = 90, there is both tangental and centripetal acceleration. How do we know the magnitude of accel won't be greater here? At this point, tangential accel should be a max and centripetal will be a min. My professor gave me a hint. Look at max forces.....I still don't get it. Thanks in advance.