Author Topic: Projectile Orbits and Satellite orbits  (Read 240491 times)

Fu-Kwun Hwang

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Projectile Orbits and Satellite orbits
« on: January 29, 2004, 06:11:39 pm »
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demo shown as Flash (5M byte)

 Newton had observed that any projectile launched horizontally is, in a sense, an Earth satellite.
 A rock thrown from a tall building sails in a modest orbit that soon intersects the earth not far from its point of launch.
 If the ball were fired more swiftly to start with, it would travel further. Futher increasing the speed would result in ever larger, rounder elliptical paths and more distant impact point. Finally, at one particular launch speed, the ball would glide out just above the planet's surface all the way around to the other side without ever striking the ground.
 At successively greater launch speeds, the ball would resolve in ever-increasing elliptical orbit until it moved so fast initally that it sailed off in an open parabolic or (if even faster) into a still flatter, hyperbolic orbit, never to come back to its starting point.
 This java applet let you change the launch speed by mouse click.
    click + to increase launch speed.
      click - to decrease launch speed.

Then Press Start to fire the ball.
 Press Reset to change parameters back to default values.
 The red arrow represents the velocity vector.
   Click the left mouse button near the tip of the
arrow and drag the mouse to change its velocity.
 Click right mouse button to stop the animation, press it again to resume.
   When will the ball start to go around without striking the ground?
   When will the motion become a circular motion? Enjoy it !
 Try to click the full checkbox, and find out what will happen.


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topic0
« Reply #1 on: January 30, 2004, 09:01:16 am »
Subject: Orbit applet
Date: Fri, 30 Jan 1998 08:44:52 +0530
From: "Surendranath Reddy.B." <bsreddy@hd1.vsnl.net.in>
To: "Hwang" <hwang@phy03.phy.ntnu.edu.tw>
Dear Mr.Hwang,
I just saw your orbit applet. It was just the thing that I thought I would suggest to you.
Please consider the following suggestions.
Would it possible to show the initial position of the projectile,
its velocity and the angle the velocity makes with the line joining it and the center of the earth
and then give the option to launch.
The distance from the center of the earth could be made large ( twice, thrice.. the radius of the earth)
It would be better if the user gives these inputs by mouse clicks or by entering the values.
( It may be also a good idea to relate these values with (gr)^0.5,
the value required for a circular orbit. One could bring out the concept of escape velocity also.
Warm Regards
Surendranath Reddy.B.

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topic0
« Reply #2 on: January 30, 2004, 09:01:45 am »
Subject: Re:Suggestions
Date: Sat, 31 Jan 1998 11:41:23 -0500
From: "Pierce C. Barnard" <pbarnard@ultranet.com>
Organization: myself
To: hwang@phy03.phy.ntnu.edu.tw
Hi, I was examining your satellite & projectile motion applet and I found it to be very useful.
A suggestion, you may want to allow a user to set all paramters and
provide a button on the applet to start the applet.
This way the user will not have to keep on readjusting the applet while the projectile is in motion.
Pierce Barnard

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topic0
« Reply #3 on: January 30, 2004, 12:50:08 pm »
Subject: Re: (no subject)
Date: Mon, 03 May 1999 18:44:25 +0200
From: Peter Brichzin <peter.brichzin@brasil.m.shuttle.de>
To: Fu-Kwun Hwang <hwang@phy03.phy.ntnu.edu.tw>
Hallo Mister Fu-Kwun Hwang,

thank you very much for sending all the files. To get a
good multimedia lesson is very important for me,
because it would be evaluated. A good evaluation will
give me a job es teacher.

I tried to understand your program. It's not easy
because my knowledge in Java is very basic. My problem
is now:
If I want to change the power of r in aceleration or
force F~ a ~ 1/r^2 to
F~ a ~ 1/r^x
then I have it to change in the method drivs of class
movingProjectile. (it works)
But this method never is called in whole
projectileOrbit.class. And to give a different exponent
to acceleration I have to give a argument to method
derivs (or are there other possibilities.

Is it possible that derivs is callt in rk4.
Could you send me please rk4.java or could you help me
in an other way with an idea to cahnge it.
Sorry that I ask you so much. Probably your time is
rare, but it would be a big help for me.
Thank you very much

Peter Brichzin

P.S: To get an imagination whatb I want I send you a
modified version: I added a Checkbox to change force.
But I can't get the connection between checkbos and
method derivs.

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satellite communication
« Reply #4 on: March 26, 2004, 08:41:05 am »
Hi, My name Joe.

do you think i have a copy of your java codes because i am tryin to do a similar project. However, on a 2d map with some predicted satellite motion.

Please help me out.

chrisdamato

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topic0
« Reply #5 on: October 09, 2005, 09:10:15 pm »
Thank you very much for creating this applet and for sharing the files!

Chris D'Amato
Rutgers University
New Jersey, USA

Chaitanya

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hello hwang sir
« Reply #6 on: October 19, 2005, 09:07:41 pm »
hello,
your animations are inimitiable....can i have a java applete for it?....i really want it..i'm a physics student and i'm studying about kepler's planetry laws...it will be a great help if u send it to me...

urs thankfully

Chaitanya

Fu-Kwun Hwang

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topic0
« Reply #7 on: October 20, 2005, 12:24:28 pm »
Just login to this forum and check out this wbe page again and click
the button "GET APPLET FILES" at the end of the first (applet) message.

arthurprs

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Re: Projectile Orbits and Satellite orbits
« Reply #8 on: September 09, 2007, 10:57:30 pm »
Hello professor, can you explain the calculations or send me the source file ?

arthurprs1991@hotmail.com

Fu-Kwun Hwang

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Re: Projectile Orbits and Satellite orbits
« Reply #9 on: September 10, 2007, 12:41:50 am »
The only equation used is F= -GMm/r2
I do not know what you would like me to explain?
Do you mean the numerical method? (I used Runge-Kutta 4th order method).

arthurprs

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Re: Projectile Orbits and Satellite orbits
« Reply #10 on: September 10, 2007, 07:28:01 am »
No angle work?

Fu-Kwun Hwang

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Re: Projectile Orbits and Satellite orbits
« Reply #11 on: September 11, 2007, 12:56:28 am »
I do not understand what do you mean by "no angle work".
Would you please write it in more detail? I only can guest what do you mean. (It is not good)  :(

If you keep click the + sign in the applet and let the velocity>=5812m/s.
The object will go around the earth and it would not fall on the earth.  :D

arthurprs

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Re: Projectile Orbits and Satellite orbits
« Reply #12 on: September 12, 2007, 10:19:01 am »
It means,
no cos and sin math to project G force to x and y axis ?

Fu-Kwun Hwang

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Re: Projectile Orbits and Satellite orbits
« Reply #13 on: September 12, 2007, 08:43:25 pm »
If you refer to the ejs code.
In the code, I calculate r=(x2+y2)1/2
,the force was calculated as F=-GMm/r2.
When I want to have x-component of the force: I use Fx=F*x/r
Similar for y-component of the force: Fy=F*y/r.
Because  x/r =cos(theta), y/r=sin(theta).

arthurprs

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Re: Projectile Orbits and Satellite orbits
« Reply #14 on: September 14, 2007, 12:43:09 am »
Tnx, thats it  :)

PS: if i could have professors like you  ???