unit Unit1;

{$mode objfpc}{$H+}

interface

uses
  Classes, SysUtils, FileUtil, Forms, Controls, Graphics, Dialogs, ExtCtrls;

type

  { TForm1 }

  TForm1 = class(TForm)
    Shape1: TShape;
    Timer1: TTimer;
    Timer2: TTimer;
    procedure FormMouseMove(Sender: TObject; Shift: TShiftState; X, Y: Integer);
    procedure Timer1Timer(Sender: TObject);
    procedure Timer2Timer(Sender: TObject);
  private
    { private declarations }
  public
    { public declarations }
  end;

const
  G = 1000000;

var
  Form1: TForm1;
  mx: double = 0;
  my: double = 0;
  x: double = 200;
  y: double = 200;
  vx: double = 0;
  vy: double = 0;

implementation

{$R *.lfm}

procedure TForm1.FormMouseMove(Sender: TObject; Shift: TShiftState; X,
  Y: Integer);
begin
  mx := x;
  my := y;
end;

procedure TForm1.Timer1Timer(Sender: TObject);
var
  dx, dy, d: double;
  ax, ay: double;
  t, r: double;
begin
  dx := mx - x;
  dy := my - y;
  d := sqrt(dx*dx + dy*dy);
  t := Timer1.Interval/1000;
  r := Shape1.Width/2;

  ax := G*dx/(d*d*d);
  ay := G*dy/(d*d*d);

  if d < 10 then begin ax:=0; ay:=0; end;

  vx := vx + ax*t;
  vy := vy + ay*t;

  x := x + vx*t;
  y := y + vy*t;

  if x < r then begin x:=r; vx:=abs(vx); end;
  if x > ClientWidth-r then begin x:=ClientWidth-r; vx:=-abs(vx); end;
  if y < r then begin y:=r; vy:=abs(vy); end;
  if y > ClientHeight-r then begin y:=ClientHeight-r; vy:=-abs(vy); end;
end;

procedure TForm1.Timer2Timer(Sender: TObject);
begin
  Shape1.Left := round(x - Shape1.Width/2);
  Shape1.Top  := round(y - Shape1.Height/2);
end;

end.