.MCAD 304020000 1 74 213 0 .CMD PLOTFORMAT 0 0 1 1 1 0 0 1 1 0 0 1 1 1 0 0 1 1 0 1 0 0 1 1 NO-TRACE-STRING 0 2 1 0 1 1 NO-TRACE-STRING 0 3 2 0 1 1 NO-TRACE-STRING 0 4 3 0 1 1 NO-TRACE-STRING 0 1 4 0 1 1 NO-TRACE-STRING 0 2 5 0 1 1 NO-TRACE-STRING 0 3 6 0 1 1 NO-TRACE-STRING 0 4 0 0 1 1 NO-TRACE-STRING 0 1 1 0 1 1 NO-TRACE-STRING 0 2 2 0 1 1 NO-TRACE-STRING 0 3 3 0 1 1 NO-TRACE-STRING 0 4 4 0 1 1 NO-TRACE-STRING 0 1 5 0 1 1 NO-TRACE-STRING 0 2 6 0 1 1 NO-TRACE-STRING 0 3 0 0 1 1 NO-TRACE-STRING 0 4 1 0 1 1 NO-TRACE-STRING 0 1 1 21 15 0 0 3 .CMD FORMAT rd=d ct=10 im=i et=3 zt=15 pr=3 mass length time charge temperature tr=0 vm=0 .CMD SET ORIGIN 0 .CMD SET TOL 0.001000000000000 .CMD SET PRNCOLWIDTH 8 .CMD SET PRNPRECISION 4 .CMD PRINT_SETUP 1.200000 1.218750 1.200000 1.200000 0 .CMD HEADER_FOOTER 1 1 *empty* *empty* *empty* 0 1 *empty* *empty* *empty* .CMD HEADER_FOOTER_FONT fontID=14 family=Arial points=10 bold=0 italic=0 underline=0 colrid=902837712 .CMD HEADER_FOOTER_FONT fontID=15 family=Arial points=10 bold=0 italic=0 underline=0 colrid=902837712 .CMD DEFAULT_TEXT_PARPROPS 0 0 0 .CMD DEFINE_FONTSTYLE_NAME fontID=0 name=Variables .CMD DEFINE_FONTSTYLE_NAME fontID=1 name=Constants .CMD DEFINE_FONTSTYLE_NAME fontID=2 name=Text .CMD DEFINE_FONTSTYLE_NAME fontID=4 name=User^1 .CMD DEFINE_FONTSTYLE_NAME fontID=5 name=User^2 .CMD DEFINE_FONTSTYLE_NAME fontID=6 name=User^3 .CMD DEFINE_FONTSTYLE_NAME fontID=7 name=User^4 .CMD DEFINE_FONTSTYLE_NAME fontID=8 name=User^5 .CMD DEFINE_FONTSTYLE_NAME fontID=9 name=User^6 .CMD DEFINE_FONTSTYLE_NAME fontID=10 name=User^7 .CMD DEFINE_FONTSTYLE fontID=0 family=Times^New^Roman points=14 bold=0 italic=0 underline=0 colrid=-1 .CMD DEFINE_FONTSTYLE fontID=1 family=Times^New^Roman points=14 bold=0 italic=0 underline=0 colrid=-1 .CMD DEFINE_FONTSTYLE fontID=2 family=Arial points=14 bold=0 italic=0 underline=0 colrid=5 .CMD DEFINE_FONTSTYLE fontID=4 family=Arial points=10 bold=0 italic=0 underline=0 colrid=-1 .CMD DEFINE_FONTSTYLE fontID=5 family=Courier^New points=10 bold=0 italic=0 underline=0 colrid=-1 .CMD DEFINE_FONTSTYLE fontID=6 family=System points=10 bold=0 italic=0 underline=0 colrid=-1 .CMD DEFINE_FONTSTYLE fontID=7 family=Script points=10 bold=0 italic=0 underline=0 colrid=-1 .CMD DEFINE_FONTSTYLE fontID=8 family=Roman points=10 bold=0 italic=0 underline=0 colrid=-1 .CMD DEFINE_FONTSTYLE fontID=9 family=Modern points=10 bold=0 italic=0 underline=0 colrid=-1 .CMD DEFINE_FONTSTYLE fontID=10 family=Times^New^Roman points=10 bold=0 italic=0 underline=0 colrid=-1 .CMD UNITS U=1 .CMD DIMENSIONS_ANALYSIS 0 0 .CMD COLORTAB_ENTRY 0 0 0 .CMD COLORTAB_ENTRY 128 0 0 .CMD COLORTAB_ENTRY 0 128 0 .CMD COLORTAB_ENTRY 128 128 0 .CMD COLORTAB_ENTRY 0 0 128 .CMD COLORTAB_ENTRY 128 0 128 .CMD COLORTAB_ENTRY 0 128 128 .CMD COLORTAB_ENTRY 128 128 128 .CMD COLORTAB_ENTRY 192 192 192 .CMD COLORTAB_ENTRY 255 0 0 .CMD COLORTAB_ENTRY 0 255 0 .CMD COLORTAB_ENTRY 255 255 0 .CMD COLORTAB_ENTRY 0 0 255 .CMD COLORTAB_ENTRY 255 0 255 .CMD COLORTAB_ENTRY 0 255 255 .CMD COLORTAB_ENTRY 255 255 255 .TXT 2 2 35 0 0 Cg a72.000000,72.000000,28 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs28 \pard {\fs20 COPYRIGHT MIRON KAUFMAN 1995}} .TXT 7 16 39 0 0 Cg a34.625000,34.625000,39 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}{\f1\fcharset0\froman Bookman Old Style;}} \plain\cf1\fs28 \pard {\f1\fs36\b Thermal Physics\par Computer Project \par Lab #1}} .TXT 15 -17 27 0 0 Cg b73.000000,73.000000,498 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}{\f1\fcharset0\froman Times New Roman;}{\f2 \fcharset2\fnil Symbol;}}\plain\cf1\fs28 \pard {\f1 We estimate the mass of the earth atmosphere by assuming the temperature to be uniform. This of course is just a first-order approximation of reality. First we get the variation of density with altitude by integrating the barometric formula dp/dh = - g}{\f2 r}{\f1 by using the equation of state of ideal gases }{\f2 r}{\f1 }{\f1 = pM/RT. So dp/dh = -(gM/RT)p. Separate the variables: dp/p = -dh/L, where L = RT/gM. Finally integrate on both sides: ln(p/p}{\f1\dn 0}{\f1 ) = -h/L or p = p}{\f1\dn 0}{\f1 exp(-h/L), and }{\f2 r} = {\f2 r}{ \dn 0}exp(-h/L). } .TXT 21 27 132 0 0 Cg a46.000000,46.000000,25 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs28 \pard This is the gas constant.} .EQN 1 -23 106 0 0 {0:R}NAME:8.3145*({0:joule}NAME)/({0:K}NAME) .EQN 5 0 133 0 0 {0:T}NAME:273*{0:K}NAME .EQN 4 0 137 0 0 {0:g}NAME={0}?_n_u_l_l_ .EQN 4 0 146 0 0 {0:M}NAME:28.8*(10)^(-3)*{0:kg}NAME .TXT 0 22 148 0 0 Cg a47.000000,47.000000,90 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs28 \pard This is the molar mass of air. Since air is mainly N{\dn 2 }the molar mass is close to 28g/mole.} .EQN 7 -23 155 0 0 {0:R.E}NAME:6.37*(10)^(6)*{0:m}NAME .TXT 0 23 157 0 0 Cg a47.000000,47.000000,25 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs28 \pard This is the earth radius.} .EQN 5 -23 156 0 0 {0:p.0}NAME:1.013*(10)^(5)*{0:Pa}NAME .TXT 0 24 158 0 0 Cg a46.000000,46.000000,32 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs28 \pard This is the atmospheic pressure. } .EQN 6 -25 152 0 0 {0:\r.0}NAME:({0:M}NAME*{0:p.0}NAME)/({0:R}NAME*{0:T}NAME) .TXT 3 23 161 0 0 Cg a47.000000,47.000000,45 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs28 \pard This is the air density at the earth surface.} .EQN 3 -23 153 0 0 {0:\r.0}NAME={0}?_n_u_l_l_ .EQN 6 0 166 0 0 {0:L}NAME:({0:R}NAME*{0:T}NAME)/({0:M}NAME*{0:g}NAME) .TXT 1 22 170 0 0 Cg a49.000000,49.000000,58 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs28 \pard L is the distance scale for atmospheric density variation.} .EQN 6 -23 168 0 0 {0:L}NAME={0}?_n_u_l_l_ .TXT 4 0 174 0 0 Cg a49.000000,49.000000,37 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}{\f1\fcharset0\fnil ;}{\f2\fcharset2\fnil Symbol;}} \plain\cf1\fs28 \pard Since h = r - R{\dn E}{\f1 the density }{\f2 r} (r) is:} .EQN 1 38 176 0 0 {0:\r}NAME({0:r}NAME):{0:\r.0}NAME*({0:e}NAME)^(-(({0:r}NAME-{0:R.E}NAME)/({0:L}NAME))) .TXT 8 -38 182 0 0 Cg a72.000000,72.000000,54 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs28 \pard We graph the atmospheric density decrease with height:} .EQN 7 -1 181 0 0 {0:r}NAME:{0:R.E}NAME,{0:R.E}NAME+{0:L}NAME*0.1;{0:R.E}NAME+2*{0:L}NAME .EQN 2 3 177 0 0 &&(_n_u_l_l_&_n_u_l_l_)&({0:\r}NAME({0:r}NAME))/({0:\r.0}NAME)@2&0&(_n_u_l_l_&_n_u_l_l_)&({0:r}NAME-{0:R.E}NAME)/({0:L}NAME) 0 1 1 1 1 0 0 1 1 0 1 1 1 1 0 0 1 1 0 1 0 0 1 1 NO-TRACE-STRING 0 2 1 0 1 1 NO-TRACE-STRING 0 3 2 0 1 1 NO-TRACE-STRING 0 4 3 0 1 1 NO-TRACE-STRING 0 1 4 0 1 1 NO-TRACE-STRING 0 2 5 0 1 1 NO-TRACE-STRING 0 3 6 0 1 1 NO-TRACE-STRING 0 4 0 0 1 1 NO-TRACE-STRING 0 1 1 0 1 1 NO-TRACE-STRING 0 2 2 0 1 1 NO-TRACE-STRING 0 3 3 0 1 1 NO-TRACE-STRING 0 4 4 0 1 1 NO-TRACE-STRING 0 1 5 0 1 1 NO-TRACE-STRING 0 2 6 0 1 1 NO-TRACE-STRING 0 3 0 0 1 1 NO-TRACE-STRING 0 4 1 0 1 1 NO-TRACE-STRING 0 1 1 52 26 14 0 3 .TXT 41 -2 183 0 0 Cg a72.000000,72.000000,43 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs28 \pard To get the mass we integrate the density: } .EQN 6 3 184 0 0 {0:m}NAME:4*{0:\p}NAME*({0:R.E}NAME&{0:\¥}NAME*{0:m}NAME`{0:\r}NAME({0:r}NAME)*({0:r}NAME)^(2)&{0:r}NAME) .TXT 12 0 185 0 0 Cg a69.000000,69.000000,180 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs28 \pard the numerical integration did not converge. To help Mathcad we try then to simplify the integral: (1) take out the constant factors; (2) change variable of integration to x = r/L.} .EQN 13 0 73 0 0 {0:m}NAME:4*{0:\p}NAME*{0:\r.0}NAME*({0:e}NAME)^(({0:R.E}NAME)/({0:L}NAME))*({0:L}NAME)^(3)*(({0:R.E}NAME)/({0:L}NAME)&{0:\¥}NAME`({0:x}NAME)^(2)*({0:e}NAME)^(-{0:x}NAME)&{0:x}NAME) .TXT 16 -4 212 0 0 Cg b73.000000,73.000000,28 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs28 \pard {\fs20 COPYRIGHT MIRON KAUFMAN 1995}} .TXT 7 1 206 0 0 Cg a72.000000,72.000000,195 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs28 \pard We still get an error message due to raising e to a large power R{\dn E}/L = 792.6. We next use the symbolic processor (MAPLE). Select the integral and then from Symbolic chose Evaluate symbolically. } .EQN 14 2 192 0 0 {0:m}NAME:4*{0:\p}NAME*{0:\r.0}NAME*({0:e}NAME)^(({0:R.E}NAME)/({0:L}NAME))*({0:L}NAME)^(3)*((2)/({0:exp}NAME(({0:R.E}NAME)/({0:L}NAME)))+(2)/({0:exp}NAME(({0:R.E}NAME)/({0:L}NAME)))*({0:R.E}NAME)/({0:L}NAME)+(1)/({0:exp}NAME(({0:R.E}NAME)/({0:L}NAME)))*( ({0:R.E}NAME)^(2))/(({0:L}NAME)^(2))) .EQN 1 88 204 0 0 ({0:R.E}NAME)/({0:L}NAME)={0}?_n_u_l_l_ .TXT 16 -88 211 0 0 Cg a70.000000,70.000000,66 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs28 \pard Finally select the equation above and use Simplify under Symbolic.} .EQN 5 1 101 0 0 {0:m}NAME:4*{0:\p}NAME*{0:\r.0}NAME*{0:L}NAME*(2*({0:L}NAME)^(2)+2*{0:R.E}NAME*{0:L}NAME+({0:R.E}NAME)^(2)) .EQN 9 1 102 0 0 {0:m}NAME={0}?_n_u_l_l_ .TXT 6 -3 115 0 0 Cg a70.000000,70.000000,94 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}{\f1\fcharset0\froman Times New Roman;}}\plain \cf1\fs28 \pard {\f1 The mass of the atmosphere is 5.3*10}{\f1\up 18}{ \f1 Kg}{\f1\up }{\f1 which is small compared to the earth mass 6*10}{ \f1\up 24}{\f1 kg. }} .TXT 45 -2 213 0 0 Cg b73.000000,73.000000,28 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs28 \pard {\fs20 COPYRIGHT MIRON KAUFMAN 1995}}