Physics Tutorial Needed

'dy : this is how far the ball moves each step
'ddy : this is how much dy will change each step
Rem
So we need to have a little ddy aka acceleration aka gravity for this case, let's make it -0.2 because we want things to fall downwards
y = 10, dy = -1, ddy = -0.2
y = 9, dy = -1.2, ddy = -0.2
y = 7.8, dy = -1.4, ddy = -0.2
y = 6.4, dy = -1.6, ddy = -0.2
...etc
Now as the ball moves down, the rate at which it moves down increases as we expect.

Same goes for throwing a ball upwards from the ground:
y = 0, dy = 1, ddy = -0.2
y = 1, dy = 0.8, ddy = -0.2
y = 1.8, dy = 0.6, ddy = -0.2
y = 2.4, dy = 0.4, ddy = -0.2
y = 2.8, dy = 0.2, ddy = -0.2
y = 3.0, dy = 0.0, ddy = -0.2
End Rem

Type GameObject
	Field x#,y#,dx#,ddx#,dy#,ddy#
	Field VDir ' 1 for up, 2 for down, 0 for still
	Field HDir ' 1 for left, 2 for right, 0 for still
	Field BB#
End Type
list:TList=CreateList()

Local Ball:GameObject = New GameObject

Ball.x# 	= 	400.0
Ball.y# 	= 	500.0
Ball.dx# 	= 	0.0
Ball.ddx#	= 	0.0
Ball.dy#	=	-10.0 ' Velocity
Ball.ddy#	=	0.5 ' Gravity
Ball.VDir	=	1
Ball.HDir	=	0
Ball.BB# 	=	-10.0 ' Bounce Velocity
Graphics 800,600,0
Repeat
	Cls
	DrawOval(ball.x#,ball.y#,20+ball.dx#+Rand(0,1),20+ball.dy#+Rand(0,1)) 
		DrawText "y = "+ball.y#+" dy ="+ball.dy#+" ddy ="+ball.ddy#,0,0
		
		If KeyDown(Key_Left)	 Ball.dx# = ball.dx# - 0.3; ball.ddx# = 0.001
		If KeyDown(Key_Right) Ball.dx# = ball.dx# + 0.3; ball.ddx# = -0.001
				
		If ball.x# < -40 Then ball.x# = 820
		If ball.x# > 840 Then ball.x# = -20
		If ball.dx# < -2 Then ball.dx# = -2
		If ball.dx# > 2 Then ball.dx# = 2
		If ball.y# > 550
			If Ball.BB# < 0
				Ball.BB#	=	Ball.BB#	+	0.9
				Ball.dy#	=	0+Ball.BB#
			EndIf
			If Ball.BB# > 0
				Ball.dy# = 0
				Ball.ddy#=0
			EndIf
		EndIf
		If KeyHit(Key_SPACE) And ball.y# > 520
			Ball.dy#=-10.0
			Ball.ddy#=0.5
			Ball.BB#=Ball.dy
		EndIf
		
		Ball.dx# = Ball.dx# + ball.ddx#
		Ball.x# = Ball.x# + Ball.dx#
		
		Ball.dy# = Ball.dy# + ball.ddy#
		Ball.y# = Ball.y# + Ball.dy#
	
	Flip
Until KeyHit(Key_ESCAPE)