wheel movement

wheel.rkt

(require 2htdp/image)
(require 2htdp/universe)

(define background (empty-scene 200 50))

(define width-of-world 200)

(define radius-of-wheel 2)

(define distance-between-wheel (* radius-of-wheel 5))

(define wheel
  (circle radius-of-wheel "solid" "red"))

(define SPACE (rectangle 5 5 radius-of-wheel "white"))

(define BOTH-WHEELS (beside wheel SPACE wheel))

(define (render x)
   (place-image wheel x 48 (empty-scene 200 50)))

(define (tock x)
 (+ 3 x))

(define (main ws)
   (big-bang ws
     (on-tick tock)
     (to-draw render)))

(main -10)