Video about pressure in kinetic theory

In summary, Francesco is looking for a video demonstrating intuition on pressure in the context of kinetic theory of gases. He recalls seeing a video where lead sinkers were poured onto a scale to show the average weight force and pressure. However, he is unable to find the video and is now looking for a similar "practical" video. He also mentions wanting an interactive applet about kinetic theory, preferably in flash, to use for educational purposes. He thanks Bystander for suggesting an applet on the second law of thermodynamics but finds it too advanced. Francesco shares several applets he has found on kinetic theory and expresses frustration at not being able to find the specific video he remembers.
  • #1
FranzDiCoccio
342
41
Hi,
I am looking for a video helping intuition on pressure, in the context of kinetic theory of gases.

I remember seeing a video where someone poured a bucketful of little hard balls (lead sinkers for fishing?) onto an electronic scales (a dynamometer, really) showing that this corresponds to an average weight force on the scales dish, and hence to a pressure (most of the balls did not stay on the dish, but bounced away).

This was a lot of time ago... I think I have seen this videe I'm talking about on a tv program or perhaps during a physics class back when I was in high school. There was no internet at the time.

I tried looking for something like that in the internet, but the only similar thing I have found so far is this video on youtube (golf ball atmosphere);
It's not exactly the same thing, though, and what's happening is not very clear to me.
Do the balls move because of a flow of air, or because they're hit by the fan blades?
Does the partition lift because of the average momentum from collisions with the balls or because someone is pulling the thread it is attached to?

Can anybody point me to an intuitive "practical" video, like the one I'm referring to?

Also, related to this, I am looking for an interactive applet about kinetic theory, possibly in flash (java is becoming a pain, because I have no control on the software in the computers I'm using, and the IT people take ages to change things).

Thanks a lot

Francesco
 
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  • #3
Hi Bystander

thanks for your reply. I have found several nice applets on kinetic theory, and they sure help intuition.
I had not found the one you're suggesting, and I think I am going to use that too. However, it is a bit too advanced, since it involves the concept of entropy.

I was thinking of a simple "practical" demonstration using macroscopic objects, like lead beads as molecules and a kitchen scales as a manometer.
That's what was used in a video I saw ages ago. I assumed that rhis is a standard demonstration in American physics classes (I am not from the USA), and that I would easily find a video . Apparently it is not...

Applets on kinetic theory I have found


Thanks again
-Franz
 

1. What is the kinetic theory of gases and how does it relate to pressure?

The kinetic theory of gases states that gas particles are constantly in random motion and collide with each other and the walls of their container. These collisions create pressure, as the particles transfer their momentum to the walls of the container. Therefore, the kinetic theory explains the relationship between the motion of gas particles and the pressure exerted by a gas.

2. How does temperature affect pressure in the kinetic theory?

According to the kinetic theory, as temperature increases, the average speed of gas particles also increases. This results in more frequent and energetic collisions with the container walls, leading to an increase in pressure. Conversely, as temperature decreases, the average speed of gas particles decreases, resulting in fewer and less energetic collisions and a decrease in pressure.

3. What is the ideal gas law and how does it relate to pressure and kinetic theory?

The ideal gas law, PV=nRT, describes the relationship between the pressure (P), volume (V), number of moles (n), temperature (T), and the gas constant (R) for an ideal gas. The ideal gas law can be derived from the kinetic theory, as it takes into account the volume of the gas particles and their average kinetic energy, which is directly related to temperature. This law helps us understand the behavior of gases in different conditions, including changes in pressure.

4. How can we measure pressure in gases using the kinetic theory?

One way to measure pressure in gases is by using a manometer, which measures the difference in pressure between the gas and the atmosphere. Another method is to use a barometer, which measures the pressure of the gas by balancing it against the pressure of a column of liquid. These measurements can then be used to calculate the pressure using the ideal gas law.

5. How does the volume of a gas affect pressure in the kinetic theory?

According to the kinetic theory, as the volume of a gas decreases, the particles have less space to move around, causing more frequent and energetic collisions with the container walls. This results in an increase in pressure. Conversely, as the volume of a gas increases, the particles have more space to move around, resulting in fewer and less energetic collisions and a decrease in pressure.

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