I was driving in a car... and thought... wow! this is a great KHV topic!

I was thinkin... whenever big rocket ships fall to earth, they hit the other particles in the air wich makes them very hot... so why whenever humans skydive... dont they spontaniously combust into a giant fire ball? cuz i mean comon... that would be EPIC!

 

Because when shuttles fall, they are traveling at slightly less than orbital speeds (the speed it takes to keep something in orbit), which are absolutely MASSIVE. Whereas, humans skydiving aren't even falling at .01% of those speeds. Luckily for us.

 

oh... gotcha...

 

turin thats only part of the answer.When space shuttles fall to earth the shuttle has to pass through many layers of the atmosphere with various gases which are flamable and through friction the shuttles ignite.Humans don't have to pass through many layers of the atmosphere and thus they stay alive.Take a human outside the atmosphere and drop them and they'll disintagrate.

 

True also.

 

gotcha cuz like. I always wanted to try skydiving... but bursting into fire wouldn't be top priority.

 

It is a more complex question than it seems. With a sky diver you aren't really going that high. This means that the air is "thicker" and so you won't reach as high a speed. Also, you have considerably less mass than a space shuttle, and so your terminal velocity (the highest speed that you can reach from simply falling through the air) is much lower. You also have a much lower surface area. All of these things combine to mean that the heat generated due to friction is small enough to be convected away by the air that you are passing through.

As for the space shuttle, it is coming from a near vacuum and entering very thin air. This means that the resistance to it's motion is less and so it can reach a higher velocity than normal. When it hits the denser/thicker air lower down the resistance increases by a considerable amount, as does the heat produced. This coupled with it's larger mass and greater surface area means that it heats up a lot more.

I'm not sure about the flammable gases combusting, but then again this is just from what I learned in physics and we never did it in any great detail.

 

im a little rusty on the subject of speeds but skydiving there is a certain meters per second per second speed of falling

 

That would be acceleration (m/s^2) and on Earth the average value is 9.81 to two decimal places. But in simpler examples 10 will often be used.

It basically means that for every second you are falling your speed will increase by 9.81 m/s. However, air resistance eventually cancels out your weight (as it increases with your speed) and you eventually reach a constant speed (your terminal velocity, assuming that you have been falling for long enough and haven't hit anything).

 

Sign me up, big boy. ;D

 

Why is the super moderator the only one spamming? >_>

;o

Interesting fact: You can fall from an aeroplane without a parachute and survive provided you land on something like snow.

 

How the hell can people spontaneously combusting be considered epic? Those are people, not inanimate objects, but people, like your family. How is that epic?

 

oh you cute little woman you. picture this in your mind. Carrottop is sitting in a giant blimp. But picture this in like family guy cartoonism. ok now picture him standing at the edge telling lame jokes. Then Bam! he falls outta the blimp. Then WOOSH! he spontanseously combusts! his giant afroish looking hair lighting aflame! The boom! he splashes into a lake. walks out and is like... "what up wit dat?" That would be EPIC!

 

I'm dead serious. I could've sworn that people could catch fire. But i just wasn't sure why they didn't. And we are discussing scientific reasons why we dont catch fire.

 

...D: I am 5'10 I am not little D:

Except that real life isn't a cartoon, in real life people wouldn't just walk out of the lake and laugh it off. They would be dead >.> which isn't epic.