Internal energy of the gas in a gasoline engine

In summary, the conversation discusses a question about the internal energy and work done by a gas in a gasoline engine's cylinder. Using the first law of thermodynamics, the participants determine that the correct answer is 109.7 J, as the work done by the gas should be subtracted from the change in energy.
  • #1
fletcher89
2
0
I am so lost with this question. Can anyone help?

The internal energy of the gas in a gasoline
engine's cylinder decreases by 176:7 J.
If 67.0 J of work is done by the gas, how
much energy is transferred as heat? Answer
in units of J
 
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  • #2
Use the first law of thermodynamic:
Q=U+W, where W is the work done by the gas
 
  • #3
I did Q= 176.7 (change in energy) + 67 (amount of work done)

I got 243.7
What am I doing wrong
 
  • #4
I think the mistake is here.
Q=U+W but since the work is fone by the gas the the +w might be deceiving.
W is positive if work is done on the gas.Since instead it is done by the gas it would imply you will have to add -67
Therefore the answer is 176.7-67=109.7
 

Related to Internal energy of the gas in a gasoline engine

1. What is the internal energy of the gas in a gasoline engine?

The internal energy of the gas in a gasoline engine refers to the total energy stored in the gas molecules due to their microscopic motion and interactions with each other.

2. How is the internal energy of the gas in a gasoline engine related to its temperature?

The internal energy of a gas is directly proportional to its temperature. As the temperature of the gas increases, the molecules gain more kinetic energy, causing an increase in internal energy.

3. Does the amount of gas in a gasoline engine affect its internal energy?

Yes, the internal energy of a gas is directly proportional to the amount of gas present. More gas means more molecules, which results in a higher internal energy.

4. How is the internal energy of a gas in a gasoline engine converted into mechanical energy?

The internal energy of the gas in a gasoline engine is converted into mechanical energy through the combustion process. When the fuel-air mixture is ignited, it undergoes a chemical reaction that releases heat energy, which is then converted into mechanical energy to power the engine.

5. Can the internal energy of a gas in a gasoline engine be changed?

Yes, the internal energy of a gas can be changed through various means such as changing the temperature, pressure, or volume of the gas. For example, a gas can be compressed to increase its internal energy, or it can be heated to increase its temperature and therefore its internal energy.

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