Flumble wrote:Neil_Boekend wrote:quantum7
How you decelerate doesn't matter. To decelerate in x seconds by y m/s you need to apply certain force.
Unless you're being caught by Superman apparently.
The "super" is for "(supermassive) black holes at my command". (either classical black holes or something with quantum gravity) He doesn't so much "fly" as he bends spacetime to make him fall in the direction he points his hands. It's an elegant explanation for why people survive being caught by him. This is now my headcannon. (same goes for The Matrix, although "it's a computer program" covers it, too)
They're still going to be ripped to shreds by the deceleration. a = v2/2x, so the faster you're falling, the greater distance you will need in order to decelerate safely, and it's a squared-term relationship.
sevenperforce wrote:Imagining that you were on the right trajectory that you could get your arms and legs around it and basically hug it tightly all the way down, what would the limiting factor be? Hug strength? Frictional heating?
If the person can feel pain, the frictional heating wins, I believe.
Not if their shirt and pants are able to be the primary contact with the flagpole.
Supposing someone has dropped from 25 stories -- five times what would be feasible with a horizontal flagpole. That's going to be a falling speed of 38 meters/second, which is still under terminal velocity. If we go with 65 kg or so for mass, then the person's kinetic energy is a nasty 95.6 kJ. That's what we need to burn off on a slide down the flagpole.
Suppose that Rex is (again) in incredibly good physical shape and can exert a lot of force on the flagpole. Weightlifters can do 400+ Newton dumbbell flies using their chest muscles and 450+ Newton bicep curls, so if we imagine that Rex is in great physical shape and can exert this kind of force with both chest and arms, and pretend his legs can exert the same kind of grip, that's 3400 Newtons total.
With a generous sliding frictional coefficient of 0.5, that's 1700 Newtons of upward force retarding his motion, for a deceleration of 26 m/s2. But gravity is still tugging him down at 9.8 m/s2, reducing his effective deceleration to only 16.3 m/s2. He's going to need 44 meters of flagpole to slow to a stop. Not gonna work out too well for Rex.
What about the temperature? Let's say Rex can manage to wrap their body completely around the flagpole, so that they're able to spread out the friction over about 1 meter of it vertically. I'm going to guesstimate the diameter of the flagpole at a good solid 15 cm (this is going to be a big flagpole), making the surface area about 0.0056 m2. Not much to work with, really. That deceleration is going to take place over only 2.33 seconds, which means we need to somehow transfer 95.6 kJ to that surface area in that time period. Not enough time for heat to dissipate at all. The specific heat of water is, of course, 4.184 J/cc/degree, so if we use this value as a ballpark and say that the heating is limited to the top 1 cm layer of clothing, then that's 56 square centimeters to work with. He can manage 234.3 Joules per degree.
Which will heat his clothing by over 400 degrees Celsius. Guess you were right.