10  COM I,Z1,B[10],C$[10],I2,A[37,61],A$[10]
11  IF A$="2" THEN 130
20  I=1
30  I2=I-I
40  MAT B=ZER
50  PRINT "'EARORB' SIMULATES A SITUATION OF A UNIT MASS (ONE KILOGRAM) MOVING IN"
60  PRINT "A CIRCULAR PATH ABOUT THE EARTH. YOU WILL BE ASKED TO DO THE FOLLOWING:"
70  PRINT TAB(3)"1. CALCULATE THE ENERGY NECESSARY TO MOVE THE UNIT MASS FROM"
80  PRINT TAB(6)"ITS INITIAL ORBIT TO ITS FINAL ORBIT (WORK DONE IN JOULES)."
90  PRINT TAB(3)"2. COMPLETE THE ASSOCIATED WORKSHEET AND CHECK YOUR ANSWER"
100  PRINT TAB(6)"WITH THE PROGRAM 'EARCK'."
110  Z1=2
120  CHAIN "$ACF-2"
130  Q=I
140  R1=INT(100*RND(0))
150  IF R1<67 THEN 130
160  R2=R1*10^5
170  GOSUB 370
180  IF B[1]>B[2] THEN 210
190  R2=INT(R2*B[2]/B[I]+.5)
200  GOTO 220
210  R2=INT(R2*B[I]/B[2]+.5)
220  GOSUB 370
230  PRINT '10"AT THIS POINT YOU MAY HAVE A PROBLEM OF STANDARD DIFFICULTY OR"
240  PRINT "ONE MORE COMPLEX (CHECK WORKSHEET FOR HINT)."
250  PRINT '10"PLEASE SELECT BY TYPING EITHER 'STANDARD' OR 'COMPLEX'.";
260  INPUT B$[I,I]
270  PRINT TAB(18)'10'10"INITIAL"TAB(36)"FINAL"
280  PRINT "SEPARATION-------"I[I];TAB(35);I[3]
290  IF B$="S" THEN 320
300  PRINT "ORBITAL SPEED----"I[2];TAB(35)"GOOD LUCK"
310  GOTO 330
320  PRINT "ORBITAL SPEED----"I[2];TAB(35);I[4]
330  PRINT '10'10"REMEMBER, YOU ARE TO CALCULATE THE ENERGY (JOULES) NECESSARY TO"
340  PRINT "TO MOVE THE OBJECT FROM THE INITIAL TO FINAL ORBIT. BE SURE TO"
350  PRINT "COMPLETE THE WORKSHEET."
360  GOTO 410
370  I[Q]=R2
380  I[Q+I]=SQR(INT((1.67*5.98*10^13)/R2+.5))
390  Q=Q+2
400  RETURN 
410  END 
