What happens to the temperature of an object in vacuum?

In summary, when an object is placed in a vacuum, its temperature will initially cool as the air is pumped out of the container. However, once a sufficient vacuum is reached and pumping stops, the object's temperature will equalize with the temperature of the container through thermal radiation. If the object's mass is significantly greater than the original air mass, its temperature will not be affected much by the air.
  • #1
petterg
162
7
Hi guys.

I was wondering, what happens to the temperature of a object if it's put into vacuum?

Say you have a box of steal (something that transfers thermal energy fast between the inside and outside).
Inside the box you have a rock. The rock is held in the center of the box using something that does not transfer any kind of thermal energy.

Outside the box there is air with constant temperature.
The box itself has the same temperature as the air outside.
The rock and the air inside the box also has the same temperature.

Now you suck the air out of the box, so the rock is left in vacuum. What will happen to the temperature of the rock?
 
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  • #3
Thank you for the reply.

If I get you right the temperature doesn't drop when the air is sucked out?

When air is compressed it's getting warmer. I would expect the opposite to happen when air is sucked out, and this would make the rock colder.
 
  • #4
It will cool while you are pumping the air out, yes. As the pressure drops, the gas in the box will, indeed, cool down and cool the rock. But this will be temporary. Once you've reached sufficient vacuum and stopped pumping, temperature between the rock and the walls will equalize due to thermal radiation.
 
  • #5
Ah. I see.
Thank you
 
  • #6
K^2 said:
It will cool while you are pumping the air out, yes. As the pressure drops, the gas in the box will, indeed, cool down and cool the rock. But this will be temporary. Once you've reached sufficient vacuum and stopped pumping, temperature between the rock and the walls will equalize due to thermal radiation.

And, if the mass of the rock is much greater than the mass of the original air, the rock will experience very little cooling by the air. If the air were somehow removed instantaneously (or at least very rapidly), the rock temperature would virtually not change at all.
 

1. What is thermal energy in vacuum?

Thermal energy in vacuum refers to the energy associated with the random motion of particles in a vacuum. It is a form of kinetic energy that arises from the movement of molecules or atoms at the atomic level. In a vacuum, there is no medium for the particles to transfer their energy to, so they continue to move with their own kinetic energy.

2. How is thermal energy in vacuum different from thermal energy in a medium?

Thermal energy in a medium, such as air or water, can be transferred through conduction, convection, or radiation. In a vacuum, there is no medium for these methods of energy transfer to occur, so thermal energy can only be transferred through radiation. This makes thermal energy in a vacuum behave differently from thermal energy in a medium.

3. Can thermal energy exist in a complete vacuum?

Yes, thermal energy can exist in a complete vacuum. Even though there is no medium for the particles to transfer their energy to, they still possess kinetic energy due to their random motion. This is why objects in space, where there is a near complete vacuum, can still have thermal energy.

4. How does thermal energy in vacuum affect objects in space?

Thermal energy in vacuum can affect objects in space in various ways. For example, it can cause objects to expand or contract as their temperature changes. It can also lead to the transfer of thermal energy between objects through radiation, which is why spacecrafts have special thermal control systems to manage their thermal energy in the extreme conditions of space.

5. Can thermal energy in vacuum be harnessed for practical use?

Yes, thermal energy in vacuum can be harnessed for practical use. For example, solar panels on satellites use thermal energy from the sun to generate electricity through the photovoltaic effect. Other technologies, such as thermoelectric generators, can also convert thermal energy into electricity in a vacuum. However, these methods require careful design and engineering to be effective in the vacuum environment.

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