Thursday, 7 September 2017

thermodynamics - Error in Sear's and Zemansky's University Physics with Modern Physics 13th Edition (Young and Freeman)?


I was reading up on the Ideal Gas Equation in University Physics with Modern Physics by Young and Freeman when I chanced upon a seemingly illogical mathematical equation.


Can anyone rectify this error? Or is it misunderstanding on my part?



Here is the portion (Page 600, Chapter 18, Equation 18.12):



$$pV = \frac{1}{2}Nm(v^2)_{av} = \frac{1}{3}N\biggl[\frac{1}{2}m(v^2)_{av}\biggr]$$



It should be clear that $\frac{1}{3} \neq (\frac{1}{3} \times \frac{1}{2})$.



Answer



Nice catch!


For reference here is the book page.


:enter image description here


See , though it may error in printing or anything else.The final equation they get $$pV=\dfrac23K_{tr}$$ is very correct.



The correct form of $eq.(18.12)$ must be $$pV=\dfrac13Nm(v^2)_{av}=\dfrac {\color{red}{\huge{2}}}3N\bigg[\dfrac12 m (v^2)_{av}\bigg]$$


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