Another try with HTDP 2nd Edition

(define BOARDWIDTH 200)
(define BOARDHEIGHT 200)
(define STARTPOSITION 50)
(define BOARDBKGR "blue")
(define GAMEBOARD (empty-scene BOARDWIDTH BOARDHEIGHT BOARDBKGR))
(define ROCKET .)
(define UFO (overlay (circle 10 "solid" "red")
				   (rectangle 40 4 "solid" "green")))
(define FLATBED (rectangle 60 10 "outline" "black"))
(define (SPACESHIP option)
  (cond
	[(= option 1) ROCKET]
	[(= option 2) UFO]))
(define SHOWNSHIP (SPACESHIP 1))
(define V 10) ;Velocity
(define A 1)  ;Acceleration
(define (distance t)  ;t = Time
  (- (* V t) (* 1/2 A (sqr t))))
(define SPACESHIP-BOTTOM (- BOARDHEIGHT (/ (image-height SHOWNSHIP) 2)))
(define (render-shownship x y)
  (place-image SHOWNSHIP x y GAMEBOARD))
(define (create-rocket-scene.v7 t)
  (cond
	[(<= (distance t) SPACESHIP-BOTTOM)
	 (render-shownship STARTPOSITION (distance t))]
	[(> (distance t) SPACESHIP-BOTTOM)
	 (render-shownship STARTPOSITION SPACESHIP-BOTTOM)]))
	

• I couldn't find a way to do one of the suggestions. Which was: How would change the program so that the rocket lands on a flat rock bed that is 10 pixels higher than the bottom of the scene? Don’t forget to change the scenery, too. When I tried adding another function call to render-shownship, I kept getting an error.
• The spaceship goes down to the bottom of the screen, then accelerates up the screen. I'm a bit lost on why that is.