In deriving the gravitational potential energy term I have a question.(adsbygoogle = window.adsbygoogle || []).push({});

[tex] W \ = \ \int_{r_1}^{r_2} \overline{F}( \overline{r}) \cdot \,d \overline{r} \ = \ \int_{y_1}^{y_2}mg \,dy [/tex]

[tex] W \ = \ \int_{y_1}^{y_2}mg\,dy [/tex]

[tex] W \ = \ mgy_2 \ - \ mgy_1 [/tex]

[PLAIN]http://img696.imageshack.us/img696/2303/workvk.jpg [Broken]

[tex] W \ = \ mgy_2 \ - \ mgy_1 \ = \ U_{grav}_2 \ - \ U_{grav}_1 [/tex]

I think I understand that y_{2}< y_{1}and that is the

reason why people write the above as:

[tex] W \ = \ mgy_1 \ - \ mgy_2 \ = \ U_{grav}_1 \ - \ U_{grav}_2 [/tex]

but is it such a crime to just be aware of the y_{2}< y_{1}and

write the equation in the more logical fashion that the straight calculation gives

you. To me it seems similar to how you rewrite the equations of constant

acceleration the standard way the calculus shows them and you mentally

set g = - 9.8 m/s²

Just like to hear some thoughts on this, thanks!

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# Homework Help: Gravitational Potential Energy Derivation question?

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