With The Dark Knight, the action-infused sequel to Batman Begins, dominating the box office in recent weeks, it’s clear that the revitalization of the new Batman franchise is no fantasy. In my opinion, The Dark Knight doesn’t quite come up to the level of its predecessor—its relentless action sequences left me a bit numb after a while, and the constant quick cutting in these scenes gives the audience too much to absorb all at once. Nevertheless, it’s got some very good performances (notably, the late Heath Ledger’s much acclaimed portrayal of the psychopathic Joker), an intricate plot and dramatic psychological conflict.
Meanwhile, the action sequences, and the use of technological gadgetry are on par with a James Bond movie, and The Dark Knight provides an ample springboard to apply some Hollywood physics. There are so many chases, collisions, jumps, flights and explosions it’s easy to highlight a few of these for some exciting physical analysis. We’ll also take a look at some of the fancy gadgets and discuss the physics (or lack thereof) behind them: There’s a lot there. So let’s highlight some relevant scenes.
Click here to delve into “The Physics of Batman.”
Adam Weiner is the author of Don’t Try This at Home! The Physics of Hollywood Movies.
Fantastic Mr. Fox
F = mg + mv2/r = 80 kg (9.8 m/s + [40 m/s]2 /20 m) ≈ 7200 N or about 1600 pounds. This means that Batman has to be capable of holding 800 pounds on each of his extended arms. Imagine lying on your back on a workout room bench holding your arms out and then having about 800 pounds of weights placed on each one. Imagine what that would do to your rotator cuffs. Now tell me that Batman doesn’t have super strength. (Interestingly in a scene early in the movie he bends the barrel of a gun with his bare hand. That’s something we’re more likely to expect from Superman!) On the other hand there is a way out of this. As Fox explains in Batman Begins, those wings are made of some fantastic and unknown material that somehow has the ability to transform loose, flexible fabric to completely rigid batwings when an electric current is applied. Now this rigidity won’t do anything to help Batman’s arms, but if there are some hinges that connect the wings to the bat suit (and it is in fact these hinges that are doing the supporting rather than Batman’s arms, which he could use only to steer) then those wings might work after all!
F = ma = mΔv/Δt = 15,000 kg (22m/s/0.1s) = 3,300,000 N or 742,000 pounds acting on the vehicle By Newton’s third law, that must be the same force experienced by the cable during the collision. For reference, in an episode of “Myth Busters,” a moving car rips through a steel cable like it’s made of paper. But clearly Batman’s cables are a lot better than that. Did Fox fabricate an appropriate material in the laboratory that can withstand the force? At present the highest tensile strength yet measured is that of carbon nanotubes, which can withstand a tension of 63 billion newtons (63,000,000,000) per square meter of cross-sectional area before rupturing. Wow! That sounds pretty promising, and although researchers have not been able to produce a cable made out of carbon nanotubes on a macroscopic scale, let’s assume Fox has. Unfortunately Batman’s cables don’t have a cross-sectional area of an entire square meter. They’re compact and portable and appear to have cross-sections much closer to a square centimeter, at best. 63 billion newtons per square meter converts to 63,000 N/cm2. That’s not nearly enough. So unless the R&D; department at Wayne Enterprises has come up with something truly phenomenal, Batman’s cable is going to snap, and the Joker is going to escape (assuming he survived the earlier collision with the front wall of the cargo bay).