- #1
doctordiddy
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Homework Statement
This question would be impossible to solve without the diagram, which I can't post so instead i'll just tell you what I have so far.
gas springs are commonly used on trunk lids of cars. They are a closed system consisting of a pressure tube and piston rod with piston, as well as nitrogen gas as an energy source.
if the nitrogen gas is compressed from initial volume Vi and initial pressure Pi to final volume Vf, as the trunk lid is slowly closed find the formula for how much energy is stored in the gas spring?
Homework Equations
pV=nRT
W=pV
The Attempt at a Solution
what I have so far is
dE(energy) = dW = -p(dV) Why is this -pdV?
pV=nRT
T= constant ---> pV = constant = PiVi Not sure what this means either
E=-∫(Vf-Vi)pdV = -PiVi∫(Vf-Vi)(dV/V) = -PiVi[ln(Vf)-ln(Vi)]
again i know this is to integrate dE into just E, but I don't really understand this process, especially E=-∫(Vf-Vi)pdV = -PiVi∫(Vf-Vi)(dV/V)
therefore E=-PiVi*ln(Vf/Vi)
So yes I'm not looking for the answer since i have it I am just confused about the work to get to the answer
PS ∫(Vf-Vi) just means ∫(Vf over Vi)