Adiabatic compression of piston and finding the velocity ratio of gas

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SUMMARY

The discussion focuses on the adiabatic compression of a piston and the calculation of the velocity ratio of gases, specifically comparing air with helium. The user observed that the velocity ratio for air was unexpectedly higher than for helium mixtures, which contradicts theoretical expectations. The calculations were based on the work equation, considering equal pressure on both sides during equilibrium. Key variables included force (F), number of gas molecules (N), mass of gas (m), molecular velocity (c), and piston velocity (v), with N calculated using the ideal gas law at a temperature of 298K.

PREREQUISITES
  • Understanding of adiabatic processes in thermodynamics
  • Familiarity with the ideal gas law (PV = nRT)
  • Knowledge of basic physics concepts related to force and motion
  • Ability to perform calculations involving gas properties and equations of state
NEXT STEPS
  • Study the principles of adiabatic compression in greater detail
  • Learn about the ideal gas law and its applications in thermodynamics
  • Explore the concept of molecular velocity and its relation to temperature
  • Investigate the effects of different gas mixtures on velocity ratios in piston systems
USEFUL FOR

Students and professionals in physics, mechanical engineering, and thermodynamics, particularly those interested in gas dynamics and piston engine efficiency.

litmusgod
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TL;DR
I am solving a problem related in finding the velocity ratio of gas molecules just after and before piston during adiabatic compression.
High pressure Gas is pumped from a vessel to a chamber consisting of piston and other side diaphragm is placed which will break at certain pressure .I was trying to find the velocity ratio of gas molecules after and before piston during compression and in different scenarios like Air -Air , Helium -Helium and Helium - Air respectively in vessel and chamber .
But when I solved, Air-Air is coming with highest velocity ratio than the others, which cannot be possible as helium - air and helium- helium is supposed to be faster.
I will attach the picture of the formula i used . It's work equation . So basically during equilibrium state the pressure acting on both side will be equal so i considered as equal work . From there i calculated it .
1000054947-01.jpeg

F is the force acting on piston
N is the number of the molecules of the gas enclosed in the cylinder.
m - mass of gas
c - velocity of molecules at temp T
v - velocity of the movement of piston
N is calculated using PV/RT with temperature as 298K
 

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