What Happens to Internal Energy in a Piston if Pressure is Increased?

In summary, increasing the pressure in a piston while keeping the temperature constant will result in the volume decreasing and the surroundings doing work on the system. This means that an equal amount of heat must be removed from the cylinder to maintain constant temperature. For an ideal gas, the internal energy will remain constant, while for a non-ideal gas, the internal energy may increase or decrease depending on the change in volume.
  • #1
Smileyxx
34
0
If the temperature is kept constant,what happens to internal energy if the pressure is increased in piston?
 
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  • #2
I believe that in this situation you'd make use of the ideal gas law.
 
  • #3
Smileyxx said:
If the temperature is kept constant,what happens to internal energy if the pressure is increased in piston?

For an ideal gas, the internal energy is a function only of temperature. If the temperature is kept constant, the internal energy is constant. From the first law, this means that the heat added is equal to the work done on the surroundings. If the pressure increases, that means that the volume is decreasing, and the surroundings are doing work on the system. This means that an equal amount of heat must be removed from the cylinder (in order to maintain constant temperature).
 
  • #4
So am i suppose to mean that the internal energy decreases because of transfer of the heat to surrounding?
 
  • #5
Smileyxx said:
So am i suppose to mean that the internal energy decreases because of transfer of the heat to surrounding?
It is being kept at a constant temperature - by your definition in the OP. Increasing the pressure involves doing work but the temperature (average KE) is being kept constant so that must mean that the added energy must be taken away by the surroundings.
Is this counter-intuitive?

I'm only repeating what's in the earlier post but you seemed to be questioning it.
 
  • #6
sophiecentaur said:
It is being kept at a constant temperature - by your definition in the OP. Increasing the pressure involves doing work but the temperature (average KE) is being kept constant so that must mean that the added energy must be taken away by the surroundings.
Is this counter-intuitive?

I'm only repeating what's in the earlier post but you seemed to be questioning it.

Ya that's what my question is. Is it correct?
 
  • #7
Two people have told you the same thing. Have you a good reason not to believe it? Show us your reasoning.
 
  • #8
sophiecentaur said:
Two people have told you the same thing. Have you a good reason not to believe it? Show us your reasoning.

I was just confused between ideal and normal gas.So for ideal gas with constant temperature ,pressure falls or rise doesn't make difference but if its not ideal gas ,pressure fall may expand volume so their is greater internal energy and vice versa? Is their any mistake in this statement?
 
  • #9
Smileyxx said:
So for ideal gas with constant temperature ,pressure falls or rise doesn't make difference but if its not ideal gas ,pressure fall may expand volume so their is greater internal energy and vice versa?

An ideal gas will also expand if the pressure is decreased while keeping the temperature constant. But the internal energy is constant, since temperature is constant, by your assumption.
 
  • #10
torquil said:
An ideal gas will also expand if the pressure is decreased while keeping the temperature constant. But the internal energy is constant, since temperature is constant, by your assumption.

Yeah i get it now.thanks :smile:
 

1. What is internal energy in a piston?

Internal energy in a piston is the sum of all the microscopic forms of energy, including kinetic and potential energy, of the particles that make up the gas inside the piston.

2. How does internal energy affect the movement of a piston?

The internal energy of a gas in a piston determines its temperature, which in turn affects the pressure and volume of the gas. As the internal energy increases, the gas molecules move faster and exert a greater force on the piston, causing it to move.

3. What factors affect the internal energy of a piston?

The internal energy of a piston is affected by the temperature, pressure, and volume of the gas inside. It is also influenced by the type of gas and the number of gas molecules present.

4. How is the internal energy of a piston measured?

The internal energy of a piston can be measured by using a thermometer to determine the temperature of the gas inside. It can also be calculated using the ideal gas law, which takes into account the pressure, volume, and number of molecules of gas present.

5. Can the internal energy of a piston be changed?

Yes, the internal energy of a piston can be changed by altering the temperature, pressure, or volume of the gas inside. This can be done by heating or cooling the gas, changing the amount of gas present, or compressing or expanding the gas.

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