Piston Pressure: Forces, Physics & Thermodynamics

In summary, the conversation is about a piston in a thermodynamics class and whether thermodynamics is considered a part of physics and if physics majors take it. There is also a question about the forces on the piston and why weight is not included in the force equation in the solution manual. The problem involves piston diameters and pressure in three chambers, with the question asking for the pressure in the first chamber.
  • #1
eurekameh
210
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http://imageshack.us/photo/my-images/40/fdsfsadf.png/
So here's an image of a piston. First of all, this is for a thermodynamics class. Is thermodynamics considered to be "physics?" Do physics majors take thermodynamics?

So my question is: When writing the forces on the piston, it is obvious that we have the pressures acting on the piston from the gases in the chambers, and also a spring force on the second piston figure. I thought it was also obvious that there is Fg = mg acting on the piston as well. However, when I peeked at the solution manual, weight is not included in the force equation. Why is this?
 
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  • #2
Post the exact text of the problem.
 
  • #3
The piston diameters in Figure are D1 = 10 cm and D2 = 4 cm. When the pressure in chamber 2 is 2000 kPa and the pressure in chamber 3 is 700 kPa, what is the pressure in chamber 1, in kPa?
 

What is piston pressure?

Piston pressure refers to the force exerted by a piston on the walls of a cylinder. It is a result of the combustion process in an engine, where the expanding hot gases push the piston down, creating pressure against the cylinder walls.

How is piston pressure calculated?

Piston pressure can be calculated using the formula P = F/A, where P is the pressure, F is the force exerted by the piston, and A is the area of the piston. The force can be determined by measuring the mass of the piston and the acceleration produced by the expanding gases.

What factors affect piston pressure?

Several factors can affect piston pressure, including the size and shape of the piston, the amount of fuel injected, the temperature and pressure of the gases, and the speed at which the piston moves. The design of the engine and the combustion process also play a role in determining piston pressure.

How does piston pressure impact engine performance?

Piston pressure is a crucial factor in determining engine performance. Higher piston pressure can result in more power and torque, but it can also put more stress on the engine components. Properly balancing piston pressure is important for achieving optimal engine performance and efficiency.

What is the relationship between piston pressure and thermodynamics?

Piston pressure is closely related to the principles of thermodynamics, specifically the first and second laws. The first law states that energy cannot be created or destroyed, only transferred or converted, which is evident in the energy transfer from the expanding gases to the piston. The second law explains the direction of heat transfer and the efficiency of energy conversion in the engine, which affects the resulting piston pressure.

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