\documentclass[12pt]{article} %,twocolumn is too scrunched. decrease margin, increase column seperation
\usepackage{verbatim} % multi-line comments
\usepackage[pdftitle={equations for fun}, pdfauthor={your name here}, pdfsubject={equations}, pdfkeywords={maxwell, lagrange}]{hyperref}
\usepackage{times}
% AMS packages and font files
\usepackage{amsmath} % necessary for gathered equations
\usepackage{amsfonts}
%% For figures
%\usepackage[dvipdfm,colorlinks=true]{hyperref}
\usepackage[dvips]{graphicx}
\usepackage[usenames,dvipsnames]{color}
\usepackage{setspace}
\begin{comment}
% 1 inch margins
\setlength{\topmargin}{-.5in}
\setlength{\textheight}{9.5in}
\setlength{\oddsidemargin}{0in}
\setlength{\textwidth}{6.5in}
\end{comment}
% maximally fill up a page
\setlength{\topmargin}{-1in}
\setlength{\textheight}{10in}
\setlength{\oddsidemargin}{-.5in}
\setlength{\textwidth}{7.5in}
%% Commonly used macros
% from https://facetsproject.org/facets/browser/trunk/docs/gsdocs/nondimtf2hall.tex
\newcommand{\pfrac}[2]{\frac{\partial #1}{\partial #2}}
\newcommand{\pfraca}[1]{\frac{\partial}{\partial #1}}
\newcommand{\pfracb}[2]{\partial #1/\partial #2}
\setlength{\columnsep}{.5in}
\begin{document}
%\twocolumn
% or you can put it in \documentclass[11pt,twocolumn]{article}
% don't hyphenate so much - default = 200, max (never hyphenate) = 10,000
\hyphenpenalty=800
\title{Physics equations}
\author{Your~Name\footnote{Electronic address:emailaddress@domain.com}}
%\affiliation{Department~of~Fun, Institution~\&~Name, City,~ST~zip}
\date{\today}
\thispagestyle{empty} % hides page number of the title page
\pagestyle{empty} % no page numbers on the following pages
%\begin{abstract}
%equations for the qualifying exam
%\end{abstract}
version 3.64, 20100208
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\section{coordinate systems}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
(from cover of \cite{GriffithED}.) Most can be found in Schaum's.
%\begin{comment}
the following is in Schaum's, pg 120
\subsection{cartesian}
\begin{equation}
dV = dx\cdot dy\cdot dz
\label{eq:cartesian_dV}
\end{equation}
%\normalsize
gradient:
%\Huge
\begin{equation}
\vec{\nabla} t = \widehat{x} \pfrac{t}{x} + \widehat{y} \pfrac{t}{y} + \widehat{z} \pfrac{t}{z} % can't seem to get \hat to work
\label{eq:cartesian_gradient}
\end{equation}
\end{document}