-- card: 9852 from stack: in
-- bmap block id: 0
-- flags: 0000
-- background id: 9670
-- name: Experiment 3
----- HyperTalk script -----
on runExperiment
  global cardClear3
  global tableIncrement3,puckIncrement3
  global puckDir

  put 180 into puckY
  put 202 into markerY
  put 30 into puckX
  put 30 into markerX
  put 1 into puckDir
  put false into cardClear3
  hide menubar
  put "Click the mouse to stop." into field "blurb"

  repeat until the mouse is down
    if puckX > 398 or markerX > 404 then exit repeat
    checkPuckPos
    put (markerX+tableIncrement3) into markerX
    put (puckX+tableIncrement3+(puckIncrement3*puckDir)) into puckX
    set the loc of button "table marker" to markerX,markerY
    set the loc of button "puck" to puckX,puckY
  end repeat

  choose browse tool
  put "Click on this field to restore the screen." into field "blurb"
  show menubar

end runExperiment

on checkPuckPos
  global barrierDistance,puckDir

  if abs((item 1 of the loc of button "puck") - (item 1 of the loc of button "table marker")) >= barrierDistance then put -(puckDir) into puckDir
end checkPuckPos



-- part 1 (button)
-- low flags: 00
-- high flags: 0000
-- rect: left=20 top=196 right=208 bottom=40
-- title width / last selected line: 0
-- icon id / first selected line: 15827 / 15827
-- text alignment: 1
-- font id: 0
-- text size: 12
-- style flags: 0
-- line height: 16
-- part name: Table marker


-- part 2 (button)
-- low flags: 00
-- high flags: 0000
-- rect: left=13 top=164 right=197 bottom=47
-- title width / last selected line: 0
-- icon id / first selected line: 22073 / 22073
-- text alignment: 1
-- font id: 0
-- text size: 12
-- style flags: 0
-- line height: 16
-- part name: puck


-- part 3 (field)
-- low flags: 81
-- high flags: 2004
-- rect: left=11 top=40 right=326 bottom=403
-- title width / last selected line: 0
-- icon id / first selected line: 0 / 0
-- text alignment: 0
-- font id: 3
-- text size: 12
-- style flags: 256
-- line height: 16
-- part name: Help


-- part contents for background part 5
----- text -----
Press this field to begin pushing the puck.

-- part contents for card part 3
----- text -----
   This experiment deals with a table which is mounted on a cart that is moving to the right with a constant velocity.  Two observers, also on the cart, are pushing a dry ice puck (which is nearly frictionless) back and forth along the line of motion of the cart.  In their frame of reference, the puck moves at the same velocity in both directions, but in the earth frame, the motion of the table must also be taken into account.
   This card simulates that experiment with a few modifications.  The white rectangle in the table is a fixed point in the center of the table, allowing you to see that the table is, in fact, moving.  The two observers have been replaced with invisible, elastic barriers.  Thus, when the center of the puck reaches a certain distance from the marker, the puck "bounces" back in the other direction.