diff --git a/food_energy.pdf b/food_energy.pdf index ea78b77..68a23a9 100644 Binary files a/food_energy.pdf and b/food_energy.pdf differ diff --git a/food_energy.synctex.gz b/food_energy.synctex.gz index 8f99132..4884bbf 100644 Binary files a/food_energy.synctex.gz and b/food_energy.synctex.gz differ diff --git a/food_energy.tex b/food_energy.tex index 6af6944..6ca4e5a 100644 --- a/food_energy.tex +++ b/food_energy.tex @@ -34,9 +34,9 @@ % AJP header %When submitting the manuscript for review, do not include the author's name or institution -\author{Nathan T. Moore} -\email{nmoore@winona.edu} -\affiliation{Physics, Winona State University, Winona, MN 55987} +%\author{Nathan T. Moore} +%\email{nmoore@winona.edu} +%\affiliation{Physics, Winona State University, Winona, MN 55987} %IOP header %%\title[How many acres of potatoes does a society need?]{How many acres of potatoes does a society need?} @@ -57,7 +57,10 @@ Science and Social Policy classes are full of bespoke units and involve many dif \section{Introduction} When the United States entered World War One one of the problems they faced was logistics. How much food do you need to ship overseas to Europe to feed a million soldiers? That early work in nutrition led to the $3000$ Calorie diet many people remember from secondary Health Education class. A bit about ``Calorie'' (uppercase) vs ``calorie'' (lowercase) units you might remember: $1~Calorie = 1~kilocalorie~(kcal)$, and a dietitian might build a $3000 kcal$ diet for a 20 year old basketball player. A \textit{calorie} is the amount of energy it takes to heat a gram of water by a degree Celsius. There are about $4.2$ Joules in a single calorie, and a Joule occurs all over introductory physics. If you need to buy a new home furnace, the sales brochure might advertise that it is capable of delivering $100,000$ BTU's of heat each hour. What's a BTU? Heat a pound of water by $1^{\circ}F$. Of course Heat Pumps are far more efficient than simply burning methane or propane, but they consume kilo-watt-hours (kWh) of electricity, not BTU's. What's a kWh? Run a $1000$ Watt toaster for an hour and you'll have pulled one kWh off the grid, it will cost you about $\$0.13$ in Minnesota. If you decide to put solar panels in your backyard, they will probably collect about $10\%$ of the $3.5kWh$ the the sun delivers to each square meter of your lawn (in Minnesota) each day. -As the previous paragraph illustrates, there are a frustratingly large number of different units in an ``Energy'' class. At Winona State, this 3 credit class fulfills a ``Science and Social Policy'' general education requirement and is taken by students from across the university. Lots of college majors don't require a math class beyond algebra or introductory statistics and the population is largely math-averse. You could jokingly say that one of the main things students learn in the class is unit conversion, but it isn't far off. Nearly every field finds energy a useful representation, and every profession has their own set of units and terminology most well suited for quick calculation. Would a medical lab scientist talk about the fractional acre-foot of urine needed test kidney function? No, but someone in the central valley of California would certainly care about the acre-feet of water necessary to grow almonds! Does a gas station price their gasoline in dollars per kWh? Given the growing electrification of cars, they might soon. +As the previous paragraph illustrates, there are a frustratingly large number of different units in an ``Energy'' class. At +XXXXXX +%Winona +State, this 3 credit class fulfills a ``Science and Social Policy'' general education requirement and is taken by students from across the university. Lots of college majors don't require a math class beyond algebra or introductory statistics and the population is largely math-averse. You could jokingly say that one of the main things students learn in the class is unit conversion, but it isn't far off. Nearly every field finds energy a useful representation, and every profession has their own set of units and terminology most well suited for quick calculation. Would a medical lab scientist talk about the fractional acre-foot of urine needed test kidney function? No, but someone in the central valley of California would certainly care about the acre-feet of water necessary to grow almonds! Does a gas station price their gasoline in dollars per kWh? Given the growing electrification of cars, they might soon. Everyone eats, maybe not $3000 kcals$ per day, but at least something every day. When I teach our energy class,\cite{Energy_textbook,PFFP} I spend a few weeks talking about food energy before all other types. While food production is not central to climate change and wars over oil, food is essential in a way that diesel and gasoline are not. Vehicle fuel makes modern life possible, but we could live, unpleasantly, without it. We can't live without fats and protein. @@ -70,7 +73,10 @@ To introduce Food Energy, I ask the students to work through a few questions: \centering \includegraphics[width=\columnwidth]{at_the_buffet.jpg} \caption{ -A proto-college-student at Winona's China King Buffet, dreaming about visiting the steam tables every day. +A proto-college-student at +XXXXX's +%Winona's +China King Buffet, dreaming about visiting the steam tables every day. } \label{buffet} \end{figure} @@ -105,7 +111,10 @@ $+3000\frac{kcal}{hour}\approx +3500W$. In medicine, these slopes are effectively equivalent to ``Metabolic Equivalent of Task'' (METS), a common measure in cardiology and exercise physiology. METS is power normalized by mass, $1METS=1\frac{kcal}{kg\cdot hour}$, and METS levels are available for many different physical activities.\cite{METS} \subsection{Burning off food energy} -Imagine that after eating a $600kcal$ bacon-maple long-john (donut), you decide to go for a hike to ``work off'' the Calories. Winona State is in a river valley bounded by $200m$ tall bluffs. How high up the bluff would you have to hike to burn off the donut? +Imagine that after eating a $600kcal$ bacon-maple long-john (donut), you decide to go for a hike to ``work off'' the Calories. +XXXXXX +%Winona +State is in a river valley bounded by $200m$ tall bluffs. How high up the bluff would you have to hike to burn off the donut? Useful information: human muscle is about $1/3$ efficient, and on Earth's surface, gravitational energy has a slope of about $10~\frac{Joules}{kg\cdot m}$. \begin{figure}[h]