A professor at the University of Minnesota is using comic book characters such as Spider-Man and Superman to teach first-year students the fundamentals of physics.

In his class, called "Everything I Know about Science I Learned From Reading Comic Books," physics professor and comic book fan Jim Kakalios examines such issues as the tensile strength of Spidey's webs and the nutritional requirements of the Flash.

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"Rather than presenting the physics as it's normally done in a traditional course, we introduce it as we need it to address problems" that present themselves in comic books, Kakalios says.

Kakalios points to the early Superman comics, in which The Man of Steel could not fly, but was so strong he could "leap tall buildings in a single bound." The comics explained this by saying Superman came from a planet with much higher gravity.

In Kakalios' class, they calculated that Superman's home planet would have to be eight times more massive than Earth to allow him to jump over skyscrapers. That poses some problems for the composition of Krypton (the planet, not the noble gas).

"You can make a planet eight times bigger, but then they tend to be gas giants, like Jupiter," Kakalios said on CBC Radio's As It Happens Thursday. "You can't really make a planet eight times denser, because the density of matter is really set by inter-atomic forces."

Kakalios says the only way to explain Krypton's huge mass is to make the planet's core out of super-dense neutron star material. This could also explain why Krypton exploded, says Kakalios, because such a planet would be intrinsically unstable.

The physics of Spider-Man

Using a more recent example, Kakalios says Spider-Man's webbing, said in the comic books to have the tensile strength of steel, could easily support his weight as he swings around Manhattan. In fact, the Spidey's webs could support a couple of tonnes.

That same webbing couldn't save Peter Parker's girlfriend, though.

In a 1973 Spider-Man comic, the Green Goblin kidnaps Gwen Stacy and takes her to the top of a bridge (a scene re-enacted in this summer's movie, with Mary Jane Watson standing in for Gwen).

When the Goblin knocks her off the bridge, Spider-Man catches her in his webbing just before she hits the water. But when Spidey pulls her up, he discovers she is dead.

Kakalios says comic book fans have argued for many years about the cause of her death. So, he calculated how fast Gwen would have been travelling near the bottom of the tower – about 150 km/h – and how much force Spider-Man's web would have exerted to stop her in an instant: about 10 times the force of gravity.

"It's actually very realistic that she died by the sudden stopping," says Kakalios.

The course tackles all sorts of superhuman powers.

The X-Men's Cyclops, who can shoot "force beams" from his eyes, would need enormous neck muscles to withstand the kickback on his head every time he used his power. Newton's third law, Kakalios points out, states that every action has an equal and opposite reaction.

Winged superheroes, such as Hawkman, would need ridiculously large chest muscles to get themselves off the ground.

And the thermodynamics of The Flash are particularly mind-boggling. In one comic book, he circled the globe in 80 seconds. One of the class's students, history major Kristin Barbieri, calculated that The Flash couldn't possibly eat enough to power such busts of speed.

Kakalios says comic book science has kept up with the times. In the 1960s, characters such as the Incredible Hulk and the Fantastic Four gained their powers through radiation. In 1962, Spider-Man was bitten by a radioactive spider to gain his powers.

However, in this summer's movie adaptation and a recent comic book "re-imagining" of Spider-Man's origins, it was a genetically modified spider that bit Peter Parker.