[tex]P_1 + \frac{1}{2} \rho (v_1)^2 + \rho g h_1 = P_2 + \frac{1}{2} \rho (v_2)^2 + \rho g h_2 [/tex](adsbygoogle = window.adsbygoogle || []).push({});

In this equation (and regular energy equations for that matter) is g= 9.8 or -9.8 m/s^2 ?

To make sense mathematically I believe it has to be 9.8 or else pressure and velocity would increase as a fluid increases its height. I think my textbook needs to define when g is negative and when it is positive can get confusing sometimes. In kinematic equations you can pick a reference frame and set it positive or negative yourself but in energy equations it can get confusing.

For example [tex] W_{gravity} = - \Delta PE [/tex] and also [tex] \Delta PE = mg \Delta y [/tex] . If it weren't for my teacher showing me that work was the magnitude of F X magnitude of distance X cosine of lesser included angle (which my book neglects to mention) I'd be completely confused.

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Potential Energy and Bernoulli

**Physics Forums | Science Articles, Homework Help, Discussion**