10 REM DRAIN  (model of draining tank)
20 CLS
30 SCREEN 1, 0: COLOR 15, 0
40 LINE (0, 0)-(319, 180), 1, B
50 Q = 150
60 K = .01
80 PSET (T, 160 - Q), 2
90 DQ = -K * Q
100 Q = Q + DQ
110 T = T + 1
120 IF T < 319 GOTO 80
125 LOCATE 2, 2: PRINT "Drain.bas"
130 SLEEP: SLEEP
140 END