The Incredible Hulk: Curiously Strong
Our expert tackles the physics behind the hero's super-strength (his magical pants are another story)
The latest cinematic version of The Incredible Hulk is due to hit theaters soon. Now, many people are aware that the most incredible thing about the Hulk is the way his pants always stay on when he expands to ten times his original volume. (If they didn’t it would make for a completely different kind of superhero.) His brute strength, however, is a close runner-up.
For a quick and impressive example, notice how at the end of the movie trailer the emotional green-skinned monster rips a car in half with his bare hands. How strong does he have to be to do this? Let’s do a rough calculation.
I looked up the tensile strength of steel and got an average value of around 500 MPa, (that’s 500 million newtons of force per square meter). This means it would take 500 million newtons (about 110 million pounds) to pull apart a beam of steel with a cross sectional area of 1.0 square meters. The total cross sectional area of actual metal in the car is probably closer to a tenth of that. That still means that the Hulk can exert a force of 11 million pounds while ripping a car in half.
This (incredible) strength also explains how he’s able to jump so high. The leg muscles are much stronger than the arms; especially when the arms are utilized to pull laterally—as they do with the car. If we assume the Hulk is able to exert 100 million pounds with his legs as he pushes off of the ground, and he applies the force for a tenth of a second we can approximate the speed with which he takes off, and thus the maximum height of his jump. Let’s also assume the mass of the Hulk is about 10 times that of Bruce Banner or 800 kg. According to Newton’s Second Law:
Fnet = Fpush – mg = ma
Plugging in the values and solving for acceleration (a) we get:
a = 560,000 m/s2 (or 56,000 g’s!)
In addition to a splitting headache, this acceleration would result in a takeoff velocity of v = at = (560,000 m/s2)(.1s) = 56,000 m/s—around five times the escape velocity from the surface of the Earth! And, still, the pants stay on . . .