In the atmosphere above 500 kilometers above the ground, temperatures can reach more than 3,000 degrees Celsius.
Suppose people are here, wearing steel coats, and can resist the low pressure of the outside world, what will happen to people in the end?
The answer is: people will freeze to death, not burn to death.
Basics 1: The temperature t of a gas (which must be in Kelvin) is directly proportional to the average kinetic energy of a single gas molecule. Or the temperature of the gas is proportional to the average energy d of a single gas molecule, i.e.:
d=bkt where k is the Boltzmann constant and k=138 10 (-23) International Units; b is the number related to the molecule, if the molecule can be seen as a particle, then b=15。
Basic knowledge 2: The number of gas molecules hitting the wall f (the number of molecules hitting the wall per unit area per unit time), the average velocity v of the molecule, and the number density n (the number of molecules per unit volume) satisfy the following relationship:
f=0.25×nv
Basic knowledge 3: Stefan-Boltzmann radiative heat transfer law: An object with a surface area of a and a temperature of t (the unit must be Kelvin) radiates outward energy h per unit time satisfies the following relation:
h=aest^4
where s is the Stefan-Boltzmann constant, s=567*10 (-8) SIU; e is the emissivity, which for steel is e=05。
Basics 4: The relationship between the average velocity v of a molecule in a gas and the temperature t (the unit must be Kelvin) is (assuming the molecule is a mass and the mass of the molecule is m):
bkt=1.5mv 2, i.e. v=(kt m) (1 2).
Basic knowledge 5: The relationship between the Kelvin temperature t and the Celsius temperature t is: t = t + 27315。
At 500 km above the ground, the molecular number density n of the gas is very low, about 1 billionth of a billionth of the molecular number density at the ground, i.e. 10 (-16). The molecular number density at the ground is 25 10 25,500 km molecular number density is n = 25×10^9。
Consider a person in this area (wearing a steel coat) who has a body temperature of 27 degrees Celsius, which means that the person's body temperature is about t1 = 300 Kelvin; The area of the person is a.
1 A person should radiate energy outward, according to the law of radiation heat transfer in Stefan-Boltzmann, the energy emitted by a person per second is:
eout=aest1 4
a×0.5×5.67*10^(-8)*300^4=230a
2 Due to the collision of gas molecules on people, the energy that gas wants to give people, the energy absorbed by people per second is:
e absorption. fad=0.25×nv×a×bkt2
fa is the number of gas molecules that collide with a person in one second, assuming that the energy carried by each gas molecule is absorbed by the person.
Suppose the mass of the gas molecule is m=46 10 (-26) SIUs (assuming a molecular weight of 28, i.e., the mass of the nitrogen molecule); The temperature of the gas is t2 = 3000 + 273 = 3273 Kelvin. From basic knowledge point 5: v=990 international units. Bring all the quantities into the above equation to get:
e absorption = 42×10^(-8) a
It can be seen that the energy e released by a person every second is much greater than the energy e absorbed by a person. As a result, people will continue to release energy to cool down, and eventually they will freeze to death.
3 When the energy absorbed and released by a person is in equilibrium, what is the temperature of a person?
Assuming that the human temperature is t3, the energy absorbed and released reaches a balance, then there is.
e release. a×0.5×5.67*10^(-8)*t3^4
e absorption = 42×10^(-8) a
From the above equation, we can get t3=11 Kelvin, converted to minus 272 degrees Celsius. In other words, when the balance of energy is reached, the temperature of the human body is minus 272 degrees Celsius. So people will freeze to death, there is no doubt about it.