How does a pressure/temperature difference cause a force?

In summary: This means that the pressure difference at the other end of the cooler is registered within a few seconds.
  • #1
xTheLuckySe7en
6
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Hello. I am inquiring about how a pressure difference between a hot room (roughly room temperature) and a cold room (roughly the temperature of a standard refrigerator) can cause a force inside the cold room when exposed to its hotter counterpart. More specifically, I would like to apply this concept to an area where I work.

I work at a grocery store and we have a large cooler that we keep produce items in. Said room is roughly 30 to 40 meters in length between one entrance (two, big flap doors) and another exit (a big, metal door that seems fitting for a butcher's shop). So, it goes from an area with room temperature to the cooler around the temperature of a refrigerator to another area with room temperature. The big metal door is always left ajar slightly, so it is not closed fully. I enter the cooler from the side with the big flap doors and almost immediately notice the big, metal door on the opposite side swing open, almost fully, to then later go back to its starting position. This same effect happens whether it is from me entering the cooler or exiting it, both using the side with the big flap doors (I never use the metal door myself).

How does the pressure difference and sudden exposure to the hot room cause the door on the opposite side to open? It feels like it would be too far of a distance to be a gust of wind from me entering the room, and I don't know why the difference in pressure on one side 40 meters away would affect the door on the opposite end so quickly.

I tried researching this part of fluid dynamics without fully reading an entire chapter on it, but am coming up short. I would greatly appreciate either a direct and in-depth answer to my question, or a referenced source to this exact topic. If possible, an explanation on a molecular level is more helpful for my comprehension. Thank you in advance for your time.
 
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  • #2
xTheLuckySe7en said:
How does the pressure difference and sudden exposure to the hot room cause the door on the opposite side to open? It feels like it would be too far of a distance to be a gust of wind from me entering the room, and I don't know why the difference in pressure on one side 40 meters away would affect the door on the opposite end so quickly.

I tried researching this part of fluid dynamics without fully reading an entire chapter on it, but am coming up short. I would greatly appreciate either a direct and in-depth answer to my question, or a referenced source to this exact topic. If possible, an explanation on a molecular level is more helpful for my comprehension. Thank you in advance for your time.
Pressure at the molecular level is the result of collisions. The particles in question have speeds of around 500m/s which is much faster than a gust of wind. There is also a large number of particles that collisions are common and the new pressure is registered rather quickly.
 
  • #3
xTheLuckySe7en said:
I don't know why the difference in pressure on one side 40 meters away would affect the door on the opposite end so quickly.
Pressure disturbances propagate at the speed of sound.
 

FAQ: How does a pressure/temperature difference cause a force?

1. How does pressure difference create a force?

Pressure is defined as the amount of force exerted over a given area. When there is a difference in pressure between two areas, the area with higher pressure will exert a force on the area with lower pressure. This force is known as pressure force, and it is created by the movement of molecules from an area of high pressure to an area of low pressure.

2. Why does an increase in temperature cause a decrease in pressure?

When the temperature of a gas increases, the molecules in the gas gain more kinetic energy and move around faster. This results in an increase in the number of collisions between the molecules and the walls of the container, which in turn increases the pressure. However, as the molecules move faster, they also exert more force on each other, causing them to spread out and take up more space. This leads to a decrease in the density of the gas and therefore a decrease in pressure.

3. How does a temperature difference create a force?

Similar to pressure, a temperature difference also creates a force known as thermal force. This is because when there is a difference in temperature between two objects, heat energy will flow from the warmer object to the cooler object. This flow of heat results in a force that pushes the two objects apart, creating a net force between them.

4. Can a pressure difference and a temperature difference work together to create a force?

Yes, a pressure difference and a temperature difference can work together to create a force. This is known as the combined gas law, which states that the pressure, volume, and temperature of a gas are all related. If one of these factors changes, it will affect the other two. For example, if you increase the temperature of a gas, it will also increase the pressure, resulting in a greater force.

5. How does the direction of the force created by a pressure/temperature difference depend on the situation?

The direction of the force created by a pressure/temperature difference depends on the specific situation. For example, if you have a container with two different gases at different temperatures, the force will depend on the difference in temperature and pressure between the two gases. If the temperature difference is greater than the pressure difference, the force will be directed towards the warmer gas. However, if the pressure difference is greater, the force will be directed towards the area of lower pressure.

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