### Author Topic: Circular motion in vertical plane  (Read 77935 times)

#### Fu-Kwun Hwang

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##### Circular motion in vertical plane
« on: June 07, 2005, 03:45:38 pm »
A small sphere of mass m is attached to the end of a cord of length R, which rotates under the influence of the gravitation force in a vertical circle about a fixed point.
This applet shows how the speed of the sphere and the tension of the cord change.-*-

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#### lookang

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##### Re: Circular motion in vertical plane
« Reply #1 on: July 13, 2010, 09:36:42 pm »
Hi Prof,
actually this applet simulate a rod instead of a string.
i check the codes, it does not model projectile motion if the tension is insufficient to provide the centripetal acceleration.
is my understanding correct?

is would be cool if u could also release a string version!

#### Fu-Kwun Hwang

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##### Re: Circular motion in vertical plane
« Reply #2 on: July 13, 2010, 10:15:09 pm »
Do you mean you want to simulate the case when the velocity is not large enough so the the particle become projectile motion?

#### lookang

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##### Re: Circular motion in vertical plane
« Reply #3 on: July 13, 2010, 10:30:21 pm »
A small sphere of mass m is attached to the end of a cord of length R, which rotates under the influence of the gravitation force in a vertical circle about a fixed point.
This applet shows how the speed of the sphere and the tension of the cord change.-*-

Yes, a cord/string version would be a good addition to your collection of simulation.

and the words in the top post should be rod instead of cord, because T can be negative to become support force on the mass m.
if cord=string then model would change to projectile motion when T - m*g*cos(theta) < m*v^2/r imply T = 0 and the motion is under gravity field only.

the difference is subtle but some sg school teacher use this example to trick the students during level test.
« Last Edit: July 13, 2010, 10:34:15 pm by lookang »

#### Fu-Kwun Hwang

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• Posts: 3062
##### Re: Circular motion in vertical plane
« Reply #4 on: July 14, 2010, 05:13:27 pm »
I did created a simulation similar to what you have described.
However, it is only available in Chinese version. ?:

I will create a new EJS version and post it here.

#### lookang

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• http://weelookang.blogspot.com
##### Re: Circular motion in vertical plane
« Reply #5 on: July 15, 2010, 02:30:40 pm »
nice!
but i need an Ejs version to work on.
i doubt i can make one with different evolution equations
np
i try to learn from http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=448.0
and http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=1803.0
thanks!
the location is Chicago,Illinois,United States, i am at Portland Oregon USA now
« Last Edit: July 15, 2010, 02:49:54 pm by lookang »

#### Fu-Kwun Hwang

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• Posts: 3062
##### Re: Circular motion in vertical plane
« Reply #6 on: July 15, 2010, 11:52:00 pm »
Are you in the U.S. for AAPT meeting now?

I just created a quick verison of what you might need.

You can drag the gray dot to different height.
The string mode is what you want.

The following applet can be used to illustrate
1. conservation of energy
2. Collision between two particles. (two partialces are the same mass in the current version. I will add options for different mass later).
3. Pendulum or circular motion in vertical plane.

Full screen applet or Problem viewing java?Add http://www.phy.ntnu.edu.tw/ to exception site list
• Please feel free to post your ideas about how to use the simulation for better teaching and learning.
• Post questions to be asked to help students to think, to explore.
• Upload worksheets as attached files to share with more users.
Let's work together. We can help more users understand physics conceptually and enjoy the fun of learning physics!

#### lookang

• Hero Member
• Posts: 1774
• http://weelookang.blogspot.com
##### Re: Circular motion in vertical plane
« Reply #7 on: July 16, 2010, 04:14:21 am »
Are you in the U.S. for AAPT meeting now?
yes, it is from 17-21 july, here earlier to buy stuff and enjoy the trip.

I just created a quick version of what you might need.

You can drag the gray dot to different height.
The string mode is what you want.

The following applet can be used to illustrate
1. conservation of energy
2. Collision between two particles. (two particles are the same mass in the current version. I will add options for different mass later).
3. Pendulum or circular motion in vertical plane.
it is awesome man! i will look at code soon

#### Fu-Kwun Hwang

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• Posts: 3062
##### Re: Circular motion in vertical plane
« Reply #8 on: July 16, 2010, 01:39:23 pm »

#### lookang

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• http://weelookang.blogspot.com
##### Re: Circular motion in vertical plane
« Reply #9 on: July 16, 2010, 02:37:43 pm »
will work on it!
the code is simply great for learning.
thanks!

U should also start a new topic as well for the google search engine to tag your fantastic applet.
or i could do for u?
« Last Edit: July 16, 2010, 02:41:24 pm by lookang »

#### Fu-Kwun Hwang

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• Posts: 3062
##### Re: Circular motion in vertical plane
« Reply #10 on: July 16, 2010, 03:22:06 pm »
You can post your modified version to a new topic.
Add collision with different mass might be too complicated for students.
I decided to keep the applet for the case of equal mass only.
It is similar to the Chinese version (single object sliding down the hill and turn into circular motion).

#### ahmedelshfie

• Hero Member
• Posts: 930
##### Re: Circular motion in vertical plane
« Reply #11 on: July 17, 2010, 12:12:55 am »
Quote
Are you in the U.S. for AAPT meeting now?
Is this AAPT meeting i find on internet by google search  http://www.aapt.org/Conferences/sm2010/upload/Program-Book-7-7-10.pdf

#### lookang

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• Posts: 1774
• http://weelookang.blogspot.com
##### Re: Circular motion in vertical plane
« Reply #12 on: July 17, 2010, 01:04:10 am »
yes!
page 91
FI05:  2:40–2:50 p.m.  Physics Educators as Designers of
Simulation Using Easy Java Simulation
Loo Kang WEE, Ministry of Education Singapore, MOE Building, 1 North
Buona Vista Dr. (S)138675, Singapore, 519935; weelookang@gmail.com
To deepen the professional practice of physics educators, we seek to high-
light the Open Source Physics (OSP) and Easy Java Simulation (Ejs) com-
munity of educators that engage, enable and empower teachers as learners
so that we can be leaders in our teaching practice. We learned through
Web 2 online collaborative means to develop simulations together with
reputable physicists through the open source digital library. By examining
the open source codes of the simulation through the Ejs toolkit, we are able
to examine and make sense of the physics from the computational models
created by practicing physicists. We will share some of the simulations that
we have remixed from existing library of simulations models into suitable
learning environments for inquiry of physics.
http://www.phy.ntnu.edu.tw/ntnujava/index.php?board=28.0

#### Fu-Kwun Hwang

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• Posts: 3062
##### Re: Circular motion in vertical plane
« Reply #13 on: July 17, 2010, 01:18:05 am »
Great! I hope you have nice trip there and I believe you will learn a lot during the meeting.  Enjoy it! :-)

#### lookang

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• http://weelookang.blogspot.com
##### Re: Circular motion in vertical plane
« Reply #14 on: July 21, 2010, 12:19:02 pm »
http://sgeducation.blogspot.com/2010/07/physics-educators-as-designers-of.html

Enjoy! Spreading the word for Open Source Physics and NTNUJAVA Virtual Physics Laboratory.
This professional learning community (PLC) in physics is simply awesome!

« Last Edit: July 21, 2010, 02:04:15 pm by lookang »