NTNUJAVA Virtual Physics Laboratory
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Author Topic: Relative Motion (frame of reference)  (Read 330540 times)
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Fu-Kwun Hwang
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on: January 29, 2004, 12:36:18 pm » posted from:,,Satellite Provider

Registed user can get files related to this applet for offline access.
Problem viewing java?Add http://www.phy.ntnu.edu.tw/ to exception site list
If java program did not show up, please download and install latest Java RUN TIME
There are 9 translations,
Higher number at the end means more translation been done.
or


Student work sheet (word)

An object may appear to have one motion to one observer

    and a different motion to a second observer,

    depending on how the two observers are moving with respect to one another.

This java applet let you view objects from different frame of reference.

Imaging there is a river in the center of the screen (yelow dots are moving with water)

    a red boat is also moving with respect to the river,
There is a person(blue) walks close to one side of the river, (S)he can swim across the river.

You can easily change frame of reference by moving your mouse to different regions.

    e.g. If you move your mouse within the river,
      YOU will becomes an observer moving with water.

      If you move your mouse into the boat region,

      You becomes on the boat watching other objects moving.

      You can walk along with that person, or just standing there on the ground.

    Try to move the mouse at different regions!
      We will do something more complicate later!
    frame of referenceGroundPersonRiverBoat
    color codeGrayBluedark GreenRed
2. If you click show checkbox ,velocity vectors for your frame of reference
    will be shown with numbers. Its color is determined by the above color codes.
3. You can pressthe mouse button to suspend the animation.
    If you press with left mouse button, animation will resume when you release it.

    If you press with right mouse button, you need to click it again.

    How to change the velocity vectors?

      Just click near the tip of the arrow, and drag it left and right.
    Please try it first! Then, we will do something more interesting!
3. There are two number near the person.
    Those are vertical and horizontal speed of that person at your frame of reference.

    While the animation is suspended :

    Click near the left leg of that person and drag the mouse up and down,

      you are changing her (his) vertical speed.
    Click with right mouse button to resume the animation,
      That person will move toward the river, then, swim across the river.

      (The horizontal speed with respect to ground will increase due to river current)

    Now, try it! And watch (her)him at different frame of references.
Here is a demo (picture) of the program.

Suggestion from Surendranath Reddy.B.:

    add a square powered moving object,
      and a smll ball(yellow) moving between object's two ends.
    You can click show checkbox for more information (velocity and position),
      click and drag the tip of velocity vector (while animation is suspended)
        to change it.
In order to demonstrate 2D relative motion, a 2D checkbox were added.

Click the 2D checkbox and a ball will be thrown upward from the above moving object.

The trajectory of the ball(blue) will be shown for you.



Subject: Re: Reaction time & car accident
Date: Mon, 25 Oct 1999 20:33:42 +0100
From: "Ray Holloway"
To: "Fu-Kwun Hwang"

I am now studying the Relative Motion applet, it is most interesting to see clearly the things we notice in everyday life.I have had some holidays boating on rivers and I can picture the effects clearly as I use the applet.While driving a boat it's speed relative to the current is most apparent, particularly when trying to moor.

Thanks again for such an interesting web site

Best Wishes Ray Holloway ray@middx.screaming.net


I hope you enjoy playing with it.

Those numbers at the left side are object's horizontal coordinates,

    and you also know the timing.
Why not copy those numbers (while animation is suspended) and make a plot out of it.

Are you going to do it?


Typical Speeds (Some numbers are left blank for you to make a good quest,OK!¡^


Motion distance travels in one seconddistance moves in one hour
Swimming sperm45 um (=10-6m)16.2 cm
snail1.5 mm (=10-3m)5.4 m
ant

turtle

1 cm

? cm

36 m

? m

Fish¡H¡H
Human walking

running

1.4 m

3.5 m

5 km

12.6 km

Flying bee5 m18 km
Porpoise swimming

Human racing

9 m

¡H

32.4km

¡H

Running cheetah29 m104 km
Falcon in a dive37 m133 km
automobile(max.)62 m223 km
commercial jet airline267 m961 km
sound (in air)340 m1224 km
surface on the earth near equator460 m1.65 106 m
SR-71reconnaissance

Moon around the earth

980

1000 m

3528 km

3.6 106 m

Earth around the Sun29 km1.04 108 m
Earth-Sun travel around ore galaxy210 km7.56 108 m
light3 108 m1.08 1012 m


Registed user can get files related to this applet for offline access.
Problem viewing java?Add http://www.phy.ntnu.edu.tw/ to exception site list
If java program did not show up, please download and install latest Java RUN TIME
There are 9 translations,
Higher number at the end means more translation been done.
or


*** There are 1 more attached files. You need to login to acces it!
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Reply #1 on: August 24, 2004, 07:14:44 pm » posted from:Lynn Haven,Florida,United States

I am a high school physics teacher and I want to use your program to create a race of atomic mosters. Please help me with this. I will give a position of authority in my new world order.
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Reply #2 on: September 07, 2005, 06:59:50 am » posted from:Taipei,T'ai-pei,Taiwan

Subject: Relative motion
Date:    Fri, 29 Oct 1999 16:32:03 -0500
From:    "Gary Richert" <grichert@sun.hazelwood.k12.mo.us>
To:      <hwang@phy03.phy.ntnu.edu.tw>

Hi,

I love your relative motion website.
I have attached a word document thatwill allow my students to work with your motion applet.
I have yet to test the document with the students.
Please let me know of any errors you find or suggestions to add tothis document.
You may alter it in any way and share it with others who may visityour web page.
Thanks for the useful class room tool.

Gary Richert
Science Teacher
Florissant, Mo.
USA
grichert@stlnet.com


Name ________________________________________ Hour _____

Relative Motion
A look at "Frames of Reference"
http://www.phy.ntnu.edu.tw/ntnujava/viewtopic.php?t=227

Introduction
An object may appear to have one motion to one observer and a differentmotion to a second observer, depending on how the two observers are movingwith respect to one another.
This java applet let you view objects from different frames of reference. Imaging there is a river in the center of the screen (yellow dots are movingwith water ¡V green area) a red boat is also moving with respect to theriver. There is a person (blue) walking close to one side of the river,(S)he can swim across the river.  You can easily change frame of referenceby moving your mouse to different regions.  e.g. If you move yourmouse within the river, YOU will become an observer moving with water. If you move your mouse into the boat region, You are on the boat (boatis your frame of reference and the boat appears to you to be at rest!)watching other objects that have motion.  The object that is theframe of reference has a velocity of 0.0 m/s.

Frame of Reference Chart
 

frame of referenceGroundPersonRiverBoat
Object color codeGrayBluedark GreenRed

Program Note:

  •  You can press the mouse button to suspend the animation.
  •  If you press with left mouse button, animation will resume when yourelease it.
  •  If you press with right mouse button, you need to click it againto resume animation.
The velocity vector arrows shown do not remain the same colors.  Whenthe ground is the frame of reference the vector arrow is BLACK.  Whatarrow color is used for the other frames of reference?  Fill in thechart below:
 
 
 
Frame of Reference
Ground
Person
River
Boat
Vector Color Code(Arrow Color)
Black
   

 
 

Click on the Info box at the top of the Applet.   Place yourmouse arrow on the ground and click your right mouse button.  Determinethe relative speed of the man, river, and boat.  Record these valuesin the data table.
Observation #1

Frame of Reference is the GROUND
 
 

Frame of Reference 
Ground 
Person 
River 
Boat 
Relative Speed 
0.0 m/s 
m/sm/sm/s

 

Click the right mouse button to resume the animation.

Observation #2
Place your mouse arrow on the river and click your right mouse button. Determine the relative speed of the ground, man, and boat.  Recordthese values in the data table.

Frame of Reference is the RIVER

Frame of Reference 
Ground 
Person 
River 
Boat 
Relative Speed 
m/s 
m/s0.0 m/sm/s

 

Analysis:
 How much velocity change (dV) occurred to the ground, man, riverand boat when the frame of reference was switched from the ground to theriver? dV =  ________________

 What factor determines the velocity (speed and direction) measuredof an object?
 
 

 When stating the speed of an object on earth, what is the frameof reference commonly used by observers?  ___________________________________

How to change the velocity vectors?
Press the right mouse button to suspend the animation.  Now clicknear the tip of the vector arrow, and drag it left or right.  Thisprocedure can be used on ground, river, man, or boat to change their velocity.
Observation #3   The Motion of an Object is Relative
With the mouse cursor on the ground (gray area) click your right mouseto stop the animation. Place your mouse arrow on the boat vector and click-and-Dragthe boat vector so that it has a velocity of 0.0 m/s (negative values indicatesthe direction is upstream). Click the right mouse button to resume theanimation.
Determine the relative speed of the boat when the mouse cursor is onthe river, ground, boat and man.  Record these values in the datatable.
 

Frame of Reference is the RIVER

Frame of Reference 
Ground 
Person 
River 
Boat 
Boat Speed
m/s 
m/sm/sm/s

Analysis:
The speed of the boat is not the same from each frame of reference. True or False?
From what frame(s) of reference is the boat stationary?  __________________________
From what frame of reference(s) is the boat moving with negative velocity?______________________________________________________________________________
From what frame of reference(s) is the boat moving with positive velocity?______________________________________________________________________________

Observation #4   The Motion of Person in Two Dimensions

Refresh the webpage ¡V Press the ¡§Refresh¡¨ button at the top or themonitor screen.
 Notice there are two number near the person (0.0 and 5.0). Those are vertical and horizontal velocity of that person at your frameof reference.  The vertical velocity is 0.0 m/s and the horizontalvelocity is 5.0 m/s.  (Positive values indicated the direction isto the right and down on the monitor screen, negative values indicate thedirection is up or left on the screen.)

While the animation is suspended :
Click near the left leg of that person and drag the mouse up and down,you are changing her (his) vertical speed.  Set the vertical motionto +10 m/s and the horizontal speed to 0.0 m/s.  Place the mouse cursorarrow on the ground and ¡K
Click with right mouse button to resume the animation,

That person will move toward the river, then, swim across the riverand return to the ground.  The motion is repeated as the animationruns.
Record the vertical and horizontal velocity of the man on ground andin the water from each of these frames of reference.

frame of reference = GroundRiverBoat 
Person¡¦s Horizontal Velocity 
When on the GROUND
m/sm/sm/s
Person¡¦s  Vertical Velocity 
When on the GROUND
m/sm/sm/s
Person¡¦s Horizontal Velocity 
When in the WATER
m/sm/sm/s
Person¡¦s  Vertical Velocity 
When in the WATER
m/sm/sm/s

  1. When does the person have only a vertical speed? ___________________________________
Why is the horizontal speed = 0.0 m/s? ____________________________________________

2.When does the person have a vertical and horizontal seed? ____________________________

3. When is his horizontal speed negative?  ____________ Why isit negative? _______________
 
 
 
 
 

Observation #4   Two Dimension Relative Motion ¡V Launchinga Projectile

In order to demonstrate 2D (two dimensional) relative motion, a 2D checkboxwere added.

Refresh the web page again.

Part A) Click the right mouse button to suspend the animation. Click the 2D checkbox.  Place the mouse cursor on the ground and clickthe right mouse button to resume the animation.   Notice a ballwill be thrown upward from the barge moving in the river. Your frame ofreference is the ground.
The trajectory of the ball (blue) will be shown to you from the frameof reference of the ground.
Describe the trajectory of the ball seen on the screen.  _____________________________
Where does the ball land when it falls? _________________________________________
Does the ball have motion in two dimension (vertical and horizontal)?________________
What do you observe to be the velocity of the barge?  ______________________________
What do you observe and conclude the horizontal velocity of the ballmust be? __________

Part B.  Refresh the webpage again.
Click the right mouse button to suspend the animation.  Clickthe 2D checkbox.  Place the mouse cursor on the River and click theright mouse button to resume the animation. Your frame of reference isnow the river.
The trajectory of the ball (blue) will be shown to you from the frameof reference of the river.
Describe the trajectory of the ball seen on the screen.  _____________________________
Where does the ball land when it falls? _________________________________________
Does the ball have motion in two dimension (vertical and horizontal)?________________
What do you observe to be the velocity of the barge?  ______________________________
What do you observe and conclude the horizontal velocity of the ballmust be? __________
 

Part C.  Refresh the web page again.
Click the right mouse button to suspend the animation.  Clickthe 2D checkbox.  Place the mouse cursor on the boat and click theright mouse button to resume the animation.   Notice a ball willbe thrown upward from the barge moving in the river. Your frame of referenceis the boat.
The trajectory of the ball (blue) will be shown to you from the frameof reference of the ground.
Describe the trajectory of the ball seen on the screen.  _____________________________
Where does the ball land when it falls? _________________________________________
Does the ball have motion in two dimension (vertical and horizontal)?________________
What do you observe to be the velocity of the barge?  ______________________________
What do you observe and conclude the horizontal velocity of the ballmust be? __________
 

Summarize the Main Ideas you learned in this virtual lab regarding howthe description of   motion depends on the frame of reference.

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binay
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Reply #3 on: May 20, 2007, 09:59:31 am »


 
dear sir
 
I have seen your java applets .sir,you have done agreat work in physics teaching. thanks,for sending applets to me.for offline use the applet does not  open .please guid me 
 
your faithfully
binay,physics teacher
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Reply #4 on: July 23, 2007, 06:00:31 pm »

You need to open the html file with your browser. (check out relativeVelocity.html)
Please read the message if the files were sent to your email account.
There is no help message if you just download it.
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crespowu
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Reply #5 on: January 22, 2008, 03:19:36 pm »

Sir,your courseware is perfect.
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Reply #6 on: November 20, 2008, 09:56:56 pm » posted from:Brockville,Ontario,Canada

You used to be able to drag the velocity vector up or down also to show relative velocity at right angles.  Can this still be done?  If not, can you make it so that it can??  Thanks
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Reply #7 on: November 21, 2008, 09:01:08 am » posted from:Taipei,T'ai-pei,Taiwan

1. Click the checkbox before 2D and also click info.
2. Right click to pause the animation
3. Click at the person and drag  to change velocity in 2D
4. Right click again to resume animation, and you will find what you want.
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Reply #8 on: May 11, 2010, 07:27:59 pm » posted from:Old Orchard Beach,Maine,United States

I love to see this stuff being shared. I had to do this exercise hundreds of times a day at sea in the Coast Guard using paper maneuvering boards available in packets of 100, or on a round 3' diameter plastic maneuvering board called a Surface Summery Plotter. First, we would graphically display our ships course and speed on the SSP or maneuvering board, then using the radar, we would plot the bearing and range of a surface contact at a 3 minute interval, measure the distance traveled, divide by 100
which produced the speed of relative motion. Parallel that line till it intersected your displayed ship's speed on the graph, graphically display the other ship's relative speed on his relative motion line and the other ship's true or magnetic course and speed would be shown on the graphic display. Once we learned the other ship's course and speed, we could set up courses to intercept it within a certain time frame, at a certain speed or avoid by a certain distance at a certain time. We also used this method for search and rescue patterns using aircraft and helicopters, and intercepting rain squalls in the south pacific to provide showers for the crew when the evaporator wasn't working right. I also taught this course at Officer Candidate School and Boatswain Mate School. What a trip. If anyone has access to a Coast Guard cutter, I'm sure they would share a paper maneuvering board. 
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Reply #9 on: September 20, 2013, 10:25:13 pm » posted from:Bangkok,Krung Thep,Thailand

ขอบคุณมากครับ
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Reply #10 on: September 20, 2013, 10:58:11 pm » posted from:Bangkok,Krung Thep,Thailand

ขอบคุณมากครับ thanks
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