set output 'drag_example.ps' 
set term postscript color 'Helvetica' 18  
set grid 
set key bot left 
set xlabel 'Time (seconds) ' 
set ylabel 'Velocity (m/s)' 
set title 'An object falling through air' 
plot [0:100][-500:0] -100*(1.0 - exp(-x/10))    with lines lw 5 t 'k = 0.10'  ,  -200*(1.0 - exp(-x/20))    with lines lw 5 t 'k = 0.05'  ,  -400*(1.0 - exp(-x/40))    with lines lw 5 t 'k = 0.02'  ,  -9.8*x    with lines lc -1 lw 5 t 'k = 0'  
set output 
quit 
