And I've also tried to answer it (regarding Silver Age versions of Superman and Supergirl).
The rest of this post is cut-and-pasted from what I've said before, in a reply in another thread. Let me know if you think I got it all wrong!
This reminds me of a scene in "Many Happy Returns," the final story arc of PAD's "Supergirl" title.
Linda Danvers (Supergirl) finds Kara Zor-El (PAD's analog of Silver Age Supergirl) in an odd situation.
From Kara's perspective: She's trying to change the motion of the entire Planet Earth so that a huge, scary, oncoming meteor will miss it entirely. She seems to feel a considerable strain from what she's doing (or trying to do) -- but she knows it isn't working yet. She also knows this feat is possible for a Kryptonian in a solar system with a yellow sun because she's seen her cousin (PAD's analog of Silver Age Superman, in an alternate timeline) do this exact stunt before!
But from Linda's perspective: Kara is upside down, as if she's doing "a handstand." Her hands are pressed against the grassy ground of the yard or meadow she's in at the moment. Her feet are sticking up in the air. Beyond that, absolutely nothing is visibly happening as a result of Kara's efforts.
After an exchange of questions and answers in which Linda learns what Kara thinks she's doing and why, Linda loses patience and says, "Okay, on your feet," yanks Kara upright, and starts saying much the same things as you did about how, even if Kara could literally move an entire planet with her bare hands (which Linda doesn't believe in the first place), then the side effects of such a sudden, drastic change in its motion would cause horrifying amounts of death and destruction in the second place!
(And in the third place, Linda's already heard a report that the JLA went out into space to deal with the giant meteor themselves, and by now they've probably finished smashing it into harmless little pebbles -- but for our purposes, that's not really the point.)
To me, the most significant thing about this amusing little scene is the fact that even though Kara thought she was making an extreme effort to push the Earth in a different direction, nothing was happening as viewed by an outside observer.
For instance, her super-strong hands weren't even pushing their way into the ground, making holes in it. And by the same token, her invulnerable body (capable of flying at super-speed as it passes right through practically any form of solid matter) was not drilling its way down below the Earth's surface at high speed. (Nor even at low speed!).
So my interpretation is that Kara wasn't really using conventional "super-strength" at all in that scene; nor was she trying to "fly straight down at high speed" in order to transfer some kinetic energy in a hurry from herself to the mass of the Earth.
Instead, she was trying to use the largely-subconscious "tactile telekinesis" of a super-powered Kryptonian. What she had seen Silver Age Superman do in the past must have been this: Shove against the surface of the Earth (or another planet) to establish physical contact while subconsciously exerting his "tactile telekinesis" to latch on to everything on or beneath the surface of the Earth (plus the entire atmosphere) and "hold it all together, relative to everything else on or in the Earth," and then start pushing that planet in a certain direction without "shaking anything up" -- it all moves in perfect harmony as part of a package deal.
I suspect that Kara didn't consciously realize these details -- she only knew that she was touching the Earth and thinking, "Move the entire planet! Move the entire planet! Move the entire planet!" as hard as she could, and she was in fact feeling a real strain on her powers -- but it wasn't budging. I presume that this was because PAD worked on the theory that his Silver Age Supergirl-analog's powers had been sharply downgraded when she made the involuntary jump from her native timeline to the modern DCU where Kryptonians don't get nearly as high-powered from yellow solar radiation as they did in the Silver Age. So Silver Age Kara's subconscious tactile telekinesis just wasn't up to the job in that time and place -- but the planet-moving stunt would have worked fine in her native universe.
That might sound shady but Supes knew that if it ever came out that he didn't have the power to move the Earth while doing a headstand, I mean handstand, then the people of the world would lose faith in him. Possibly even turning against him! What's more Supes also knew that the people of Earth couldn't know that the planet was resting on the back of gigantron turtle. If that ever came out people would lose their minds. So Supes and the turtle concocted this little deal and BOOM, the rest is history.
That's my take on it away.
I present you with the following visual testimony regarding the pain in the ass that is Superman's cape:
So I still haven't read anything from the "new 52" titles -- except in the sense that occasionally I see someone has posted a scan of one page to illustrate a point.
After "Infinite Crisis" and "52", the cape was indeed made of Kryptonian fabric that was very strong, but could be damaged if exposed to Kryptonite or put through the wringer hard. The cape in Action Comics as part of the DCnU, is his baby blanket and thus invulnerable. The cape seen in Justice League and in Superman, though, that might be plain ordinary fabric. It's longer than the blanket which isn't very long in AC.
My understanding of drag seems to be; if the body is parallel to the prevailing velocity of the surrounding "liquid''s movement, then the drag coefficient is virtually zero. Since Superman usually flies parallel to the wind, the cape would have no drag until he goes perpendicular (i.e. to land or talk to a villain in mid-air, at which point he has negatively accelerated to be able to have the sound of his voice carry to the villain before he hits him with his fist.) Again, with no movement, virtually no drag again.
"Make yourself comfortable, I haven’t time to attend to it." - With these words, a legend was born.