Hints for Lesson 1.09

• G.3 The problem plotting ellipses has had unfixed errors in it for a long time. See Errata and Enhancements for two of them.
• G.6.b.ii After you do the solve (it's in the hint), you get a bunch of { d = something , t=something } pairs of solutions. Just write down what the symbols mean things mean. It will help you keep things straight.
  • d = delay between first and second shot
  • t = time both shots are at ground level (they are together because the two equations you solved were for first shot height and second shot height both being zero at the given time and for the given delay)

  Now remember that this "t" should really be called something like "tFinal"... the times that the cannonballs are in the air are actually from time 0 up to this time "tFinal" that you found.

  You will need to choose s and z values to make your plots. Good choices would be things like you saw in the earlier parts.

  Make the plots for all of the {d,t} pairs and explain why some of them don't really represent solutions that work in the real world.

  For example, the solution {d=0, t=0} just means that firing the first shot, waiting no time, and firing the second shot results in them both being at ground level when they start. (Make sense?)