Cambridge Physics Problems 22: SHM in ideal gas piston
Physics and electronics discussion, revision, exam and homework help.
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Re: Cambridge Physics Problems 22: SHM in ideal gas pistonYou haven't explained where line 2 comes from.(Original post by johnconnor92)


Can anyone please confirm with me my attempt at this question?thank you!
You haven't explained where line 5 comes from.
To get line 2 you need to start from

expand the brackets and ignore the term with both delta p and delta V in it.
The force on the piston from the gas on the right is given by
F=δpA
Sub δp from your line 2 formula
sub δV = Aδl (δl is the displacement of the piston to the right)
Sub V=Al
Then acceleration = F/m
This will give you
a = -2pAδl / lm (there is a force from the gas on the left too)
This is SHM and you can compare with the simple pendulum to get the length of the equivalent pendulum. -
Re: Cambridge Physics Problems 22: SHM in ideal gas pistonBrilliant. Thank you so much Stonebridge. I owe you a big one.(Original post by Stonebridge)
You haven't explained where line 5 comes from.
To get line 2 you need to start from

expand the brackets and ignore the term with both delta p and delta V in it.
The force on the piston from the gas on the right is given by
F=δpA
Sub δp from your line 2 formula
sub δV = Aδl (δl is the displacement of the piston to the right)
Sub V=Al
Then acceleration = F/m
This will give you
a = -2pAδl / lm (there is a force from the gas on the left too)
This is SHM and you can compare with the simple pendulum to get the length of the equivalent pendulum.