Potential & Kinetic Energy in Gas Tanks: A Comparison

In summary: Did you understand chroot's answer? He said "In a scuba tank, the stored energy is potential energy." His comment about the velocity of the molecules depending on temperature rather than pressure was irrelevant to that.Excellent question! Gas pressurized in a tank contains energy that is available to do mechanical work. If that is your definition of potential energy, then you have it. But such labels do not inform one of the physics. Most of the energy is contained in the kinetic energy of the gas molecules, so you could call it kinetic energy as well. Allowing the gas to expand cools it and uses up some of the molecules' kinetic energy. Here's how that works: Imagine a piston forming one wall of the container
  • #1
mee
213
1
Is the gas in a scuba tank or a butane lighter potential or kinetic energy? Not including gravitational effects.
 
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  • #2
First, a butane lighter is not really just pressurized gas; the butane is a liquid at only a moderate pressure.

In a scuba tank, the stored energy is potential energy. The gas particles have velocities which do not depend upon the pressure, only the temperature.

- Warren
 
  • #3
chroot said:
First, a butane lighter is not really just pressurized gas; the butane is a liquid at only a moderate pressure.

In a scuba tank, the stored energy is potential energy. The gas particles have velocities which do not depend upon the pressure, only the temperature.

- Warren

Then why does air attempt to escape violently from a fully pressurized scuba tank into the atmosphere and not from one that has equalized pressure? I mean, one could power a generator with pressurized air and not with one that has equalized pressure? Sorry if I'm misunderstanding you but I am a novice.
 
  • #4
mee said:
I mean, one could power a generator with pressurized air and not with one that has equalized pressure?

Then it would be kinetic energy. As you release the pressurised air into the gereator, it will make the generator move. At the same time, the pressure inside the tank drops. This is an example of potential energy being converted into kinetic.
 
  • #5
mee said:
Then why does air attempt to escape violently from a fully pressurized scuba tank into the atmosphere and not from one that has equalized pressure? I mean, one could power a generator with pressurized air and not with one that has equalized pressure? Sorry if I'm misunderstanding you but I am a novice.

Did you understand chroot's answer? He said "In a scuba tank, the stored energy is potential energy." His comment about the velocity of the molecules depending on temperature rather than pressure was irrelevant to that.
 
  • #6
Halls,

I was just trying to slam home the idea that it's not the kinetic energy of the little gas particles that gives a scuba tank its energy.

- Warren
 
  • #7
Why is it not, at least in part, because of the kinetic energy of the gas molecules? When the gas is released, if it does work equal to the change in potential energy, and no outside energy (such as heat) is added, the gas will be much cooler than when it was compressed, meaning it the speed of the particles has decreased.
 
  • #8
mee said:
Is the gas in a scuba tank or a butane lighter potential or kinetic energy? Not including gravitational effects.
Excellent question! Gas pressurized in a tank contains energy that is available to do mechanical work. If that is your definition of potential energy, then you have it. But such labels do not inform one of the physics. Most of the energy is contained in the kinetic energy of the gas molecules, so you could call it kinetic energy as well. Allowing the gas to expand cools it and uses up some of the molecules' kinetic energy. Here's how that works: Imagine a piston forming one wall of the container. Gas particles bounce off the piston, and their collective effect is a force on the piston. Now allow the piston to be moving. Gas particles hitting the piston will now bounce off with a slightly reduced speed because of the piston motion.

There is also a small component of negative potential energy from the fact that the gas molecules attract each other. It therefore requires energy to separate them. This is the effect that cools the gas on free expansion through a valve. It is a side issue, because even if the gas molecules did not attract each other, you could still recover energy from letting the gas expand.
 

1. What is potential energy in a gas tank?

Potential energy in a gas tank refers to the stored energy in the form of gasoline or other fuel. This energy is not being used at the moment, but has the potential to be converted into kinetic energy to power a vehicle.

2. What is kinetic energy in a gas tank?

Kinetic energy in a gas tank is the energy produced when the potential energy of the fuel is converted into motion. This energy is used to power the vehicle and keep it moving.

3. How are potential and kinetic energy related in gas tanks?

Potential and kinetic energy in gas tanks are related in that potential energy is converted into kinetic energy to power the vehicle. The potential energy stored in the gas tank is released and converted into kinetic energy as the fuel is burned and the vehicle moves.

4. Which type of energy is more important in a gas tank?

Both potential and kinetic energy are important in a gas tank. Potential energy is necessary to store the fuel and provide the initial energy for the vehicle, while kinetic energy is crucial for keeping the vehicle moving and powering its various functions.

5. How does the potential and kinetic energy in a gas tank compare to other forms of energy?

The potential and kinetic energy in a gas tank is a type of mechanical energy, which involves the movement of objects. It is also a form of chemical energy, as the fuel is a chemical compound that is converted into energy. Other forms of energy include thermal energy, electrical energy, and nuclear energy.

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