vb中怎么让一个小火箭的图片 运动到上面的云朵图片下面一点 运动过程中越来越快 到达云朵时停止

添加两个PictureBox，一个CommandButton，一个Timer
Picture2的位置在Picture1的下方
Private Sub Command1_Click()
Timer1.Enabled = True
End Sub
Private Sub Form_Load()
Timer1.Enabled = False
Timer1.Interval = 1000
End Sub
Private Sub Timer1_Timer()
Picture2.Top = Picture2.Top - 5 * 15 '每次移动5个像素
Timer1.Interval = Timer1.Interval - 30
If Timer1.Interval <= 50 Then Timer1.Interval = 50
If Picture2.Top <= Picture1.Top + Picture1.Height Then Timer1.Enabled = False
End Sub