If anyone were to actually try to run as fast as The Flash, the friction caused by air molecules would immediately set them on fire. If Superman were to try and stop a speeding train by standing in front 0f it with his hands extended in front of him, in reality he wouldn't so much stop the train as send his arms shooting straight through the front of it. The fact of the matter is that superhero physics and real world physics tend to clash a bit. And yes, that includes superhero films directed by filmmakers who want to do everything in their power to make the story seem like it's set in reality.
The sad truth is that while Batman, as seen in Batman Begins, The Dark Knight and the upcoming The Dark Knight Rises, could actually fly using his cape, it would likely result in a very painful death. Reuters has learned of a group of British physics students who decided to try and figure out if it were actually possible for the Caped Crusader to fly with the equipment provided to him in Christopher Nolan's Batman trilogy. What they found is that if the hero were to jump from 150-metres he would be able to glide 350 metres with a 4.7 metre cape. Unfortunately he would eventually hit an uncontrollable speed of 68 mph and "[hit] the ground at a life-threatening speed of 50 mph."
Said David Marshall, one of the students, "If Batman wanted to survive the flight, he would definitely need a bigger cape. Or if he preferred to keep his style intact he could opt for using active propulsion, such as jets to keep himself aloft."
