- #1
Tangeton
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So there is a divide for adiabetic expansions where a cotton wool is placed at the end of a plastic tube, and a plunger is pushed quickly down the tube compressing the air and igniting the wool when it reaches the end.
''Use the first law of thermodynamics to explain why the cotton wool will not ignite if the plunger is pushed down on the tube very slowly''
First law is U = Q + W.
So I know that if it is pushed slowly there will be some heat transfer so the compression won't be adiabatic anymore. I know that temperature is internal energy so in the case of slow expansion there is not enough of internal energy to ignite cotton.
But I don't know how to explain it in terms of the first law, since I don't know how to relate W and Q into my explanation... Could anyone help please?
''Use the first law of thermodynamics to explain why the cotton wool will not ignite if the plunger is pushed down on the tube very slowly''
First law is U = Q + W.
So I know that if it is pushed slowly there will be some heat transfer so the compression won't be adiabatic anymore. I know that temperature is internal energy so in the case of slow expansion there is not enough of internal energy to ignite cotton.
But I don't know how to explain it in terms of the first law, since I don't know how to relate W and Q into my explanation... Could anyone help please?